Move feature tutorials to what's new (#23434)

* Move tutorials to what's new

These tutorials guide readers to explore new features. Put them under the whats-new section for better visibility.

* fix build errors

mostly moving the snippet folders. Also, fix a few links.

* fix one last build warning

* Apply suggestions from code review

Co-authored-by: Tom Dykstra <tdykstra@microsoft.com>

Co-authored-by: Tom Dykstra <tdykstra@microsoft.com>

Author: BillWagner

.openpublishing.redirection.json

@@ -2980,7 +2980,27 @@
         },
         {
             "source_path": "docs/csharp/tutorials/default-interface-members-versions.md",
-            "redirect_url": "/dotnet/csharp/tutorials/default-interface-methods-versions"
+            "redirect_url": "/dotnet/csharp/whats-new/tutorials/default-interface-methods-versions"
+        },
+        {
+            "source_path": "docs/csharp/tutorials/generate-consume-asynchronous-stream.md",
+            "redirect_url": "/dotnet/csharp/whats-new/tutorials/generate-consume-asynchronous-stream"
+        },
+        {
+            "source_path": "docs/csharp/tutorials/mixins-with-default-interface-methods.md",
+            "redirect_url": "/dotnet/csharp/whats-new/tutorials/mixins-with-default-interface-methods"
+        },
+        {
+            "source_path": "docs/csharp/tutorials/nullable-reference-types.md",
+            "redirect_url": "/dotnet/csharp/whats-new/tutorials/nullable-reference-types"
+        },
+        {
+            "source_path": "docs/csharp/tutorials/ranges-indexes.md",
+            "redirect_url": "/dotnet/csharp/whats-new/tutorials/ranges-indexes"
+        },
+        {
+            "source_path": "docs/csharp/tutorials/upgrade-to-nullable-references.md",
+            "redirect_url": "/dotnet/csharp/whats-new/tutorials/upgrade-to-nullable-references"
         },
         {
             "source_path": "docs/csharp/tutorials/exploration/csharp-6.yml",
@@ -2990,6 +3010,18 @@
             "source_path": "docs/csharp/tutorials/exploration/csharp-7.yml",
             "redirect_url": "/dotnet/csharp/whats-new/csharp-7"
         },
+        {
+            "source_path": "docs/csharp/tutorials/exploration/patterns-objects.md",
+            "redirect_url": "/dotnet/csharp/whats-new/tutorials/patterns-objects"
+        },
+        {
+            "source_path": "docs/csharp/tutorials/exploration/records.md",
+            "redirect_url": "/dotnet/csharp/whats-new/tutorials/records"
+        },
+        {
+            "source_path": "docs/csharp/tutorials/exploration/top-level-statements.md",
+            "redirect_url": "/dotnet/csharp/whats-new/tutorials/top-level-statements"
+        },
         {
             "source_path": "docs/csharp/tutorials/intro-to-csharp/index.md",
             "redirect_url": "/dotnet/csharp/tour-of-csharp/tutorials/"
@@ -3026,7 +3058,10 @@
             "source_path": "docs/csharp/tutorials/intro-to-csharp/arrays-and-collections.md",
             "redirect_url": "/dotnet/csharp/tour-of-csharp/tutorials/arrays-and-collections"
         },
-
+        {
+            "source_path": "docs/csharp/tutorials/index.md",
+            "redirect_url": "/dotnet/csharp/tutorials/intro-to-csharp/introduction-to-classes"
+        },
         {
             "source_path": "docs/csharp/tutorials/intro-to-csharp/interpolated-strings-local.md",
             "redirect_url": "/dotnet/csharp/tutorials/exploration/interpolated-strings-local"

docs/core/whats-new/dotnet-core-3-0.md

@@ -26,8 +26,8 @@ C# 8.0 is also part of this release, which includes the [nullable reference type
 
 Tutorials related to C# 8.0 language features:
 
-- [Tutorial: Express your design intent more clearly with nullable and non-nullable reference types](../../csharp/tutorials/nullable-reference-types.md)
-- [Tutorial: Generate and consume async streams using C# 8.0 and .NET Core 3.0](../../csharp/tutorials/generate-consume-asynchronous-stream.md)
+- [Tutorial: Express your design intent more clearly with nullable and non-nullable reference types](../../csharp/whats-new/tutorials/nullable-reference-types.md)
+- [Tutorial: Generate and consume async streams using C# 8.0 and .NET Core 3.0](../../csharp/whats-new/tutorials/generate-consume-asynchronous-stream.md)
 - [Tutorial: Use pattern matching to build type-driven and data-driven algorithms](../../csharp/tutorials/pattern-matching.md)
 
 Language enhancements were added to support the following API features detailed below:
@@ -450,7 +450,7 @@ There's also the <xref:System.Range?displayProperty=nameWithType> type, which co
 var slice = a[i1..i2]; // { 3, 4, 5 }
 ```
 
-For more information, see the [ranges and indices tutorial](../../csharp/tutorials/ranges-indexes.md).
+For more information, see the [ranges and indices tutorial](../../csharp/whats-new/tutorials/ranges-indexes.md).
 
 ### Async streams
 
@@ -470,7 +470,7 @@ async IAsyncEnumerable<int> GetBigResultsAsync()
 
 In addition to being able to `await foreach`, you can also create async iterators, for example, an iterator that returns an `IAsyncEnumerable/IAsyncEnumerator` that you can both `await` and `yield` in. For objects that need to be disposed, you can use `IAsyncDisposable`, which various BCL types implement, such as `Stream` and `Timer`.
 
-For more information, see the [async streams tutorial](../../csharp/tutorials/generate-consume-asynchronous-stream.md).
+For more information, see the [async streams tutorial](../../csharp/whats-new/tutorials/generate-consume-asynchronous-stream.md).
 
 ### IEEE Floating-point
 

docs/csharp/language-reference/operators/await.md

@@ -55,4 +55,4 @@ For more information, see the [Await expressions](~/_csharplang/spec/expressions
 - [Asynchronous programming](../../async.md)
 - [Async in depth](../../../standard/async-in-depth.md)
 - [Walkthrough: accessing the Web by using async and await](../../programming-guide/concepts/async/index.md)
-- [Tutorial: Generate and consume async streams using C# 8.0 and .NET Core 3.0](../../tutorials/generate-consume-asynchronous-stream.md)
+- [Tutorial: Generate and consume async streams using C# 8.0 and .NET Core 3.0](../../whats-new/tutorials/generate-consume-asynchronous-stream.md)

docs/csharp/language-reference/operators/member-access-operators.md

@@ -176,7 +176,7 @@ Available in C# 8.0 and later, the `^` operator indicates the element position f
 
 As the preceding example shows, expression `^e` is of the <xref:System.Index?displayProperty=nameWithType> type. In expression `^e`, the result of `e` must be implicitly convertible to `int`.
 
-You can also use the `^` operator with the [range operator](#range-operator-) to create a range of indices. For more information, see [Indices and ranges](../../tutorials/ranges-indexes.md).
+You can also use the `^` operator with the [range operator](#range-operator-) to create a range of indices. For more information, see [Indices and ranges](../../whats-new/tutorials/ranges-indexes.md).
 
 ## Range operator ..
 
@@ -194,7 +194,7 @@ You can omit any of the operands of the `..` operator to obtain an open-ended ra
 
 [!code-csharp[ranges with omitted operands](snippets/shared/MemberAccessOperators.cs#RangesOptional)]
 
-For more information, see [Indices and ranges](../../tutorials/ranges-indexes.md).
+For more information, see [Indices and ranges](../../whats-new/tutorials/ranges-indexes.md).
 
 ## Operator overloadability
 

docs/csharp/nullable-references.md

@@ -210,6 +210,6 @@ In the preceding example, the declaration of the array shows it holds non-nullab
 ## See also
 
 - [Draft nullable reference types specification](~/_csharplang/proposals/csharp-9.0/nullable-reference-types-specification.md)
-- [Intro to nullable references tutorial](tutorials/nullable-reference-types.md)
+- [Intro to nullable references tutorial](whats-new/tutorials/nullable-reference-types.md)
 - [Migrate an existing codebase to nullable references](tutorials/upgrade-to-nullable-references.md)
 - [**Nullable** (C# Compiler option)](language-reference/compiler-options/language.md#nullable)

docs/csharp/programming-guide/interfaces/index.md

@@ -45,7 +45,7 @@ A base class can also implement interface members by using virtual members. In t
 
 An interface has the following properties:
 
-- An interface is typically like an abstract base class with only abstract members. Any class or struct that implements the interface must implement all its members. Optionally, an interface may define default implementations for some or all of its members. For more information, see [default interface methods](../../tutorials/default-interface-methods-versions.md).
+- An interface is typically like an abstract base class with only abstract members. Any class or struct that implements the interface must implement all its members. Optionally, an interface may define default implementations for some or all of its members. For more information, see [default interface methods](../../whats-new/tutorials/default-interface-methods-versions.md).
 - An interface can't be instantiated directly. Its members are implemented by any class or struct that implements the interface.
 - A class or struct can implement multiple interfaces. A class can inherit a base class and also implement one or more interfaces.
 

docs/csharp/toc.yml

@@ -35,41 +35,55 @@ items:
         href: tour-of-csharp/tutorials/branches-and-loops-local.md
       - name: List collections
         href: tour-of-csharp/tutorials/arrays-and-collections.md
+- name: What's new in C#
+  items:
+  - name: C# 9.0
+    displayName: what's new
+    href: whats-new/csharp-9.md
+  - name: C# 8.0
+    href: whats-new/csharp-8.md
+  - name: C# 7.0-7.3
+    href: whats-new/csharp-7.md
+  - name: Compiler breaking changes
+    href: whats-new/breaking-changes.md
+  - name: C# Version History
+    href: whats-new/csharp-version-history.md
+  - name: Relationships to .NET library
+    href: whats-new/relationships-between-language-and-library.md
+  - name: Version compatibility
+    href: whats-new/version-update-considerations.md
+  - name: Tutorials
+    items:
+    - name: Explore record types
+      href: whats-new/tutorials/records.md
+    - name: Explore top level statements
+      href: whats-new/tutorials/top-level-statements.md
+    - name: Explore patterns in objects
+      href: whats-new/tutorials/patterns-objects.md
+    - name: Safely update interfaces with default interface methods
+      href: whats-new/tutorials/default-interface-methods-versions.md
+    - name: Create mixin functionality with default interface methods
+      href: whats-new/tutorials/mixins-with-default-interface-methods.md
+    - name: Explore indexes and ranges
+      href: whats-new/tutorials/ranges-indexes.md
+    - name: Work with nullable reference types
+      href: whats-new/tutorials/nullable-reference-types.md
+    - name: Upgrade an app to nullable reference types
+      href: whats-new/tutorials/upgrade-to-nullable-references.md
+    - name: Generate and consume asynchronous streams
+      href: whats-new/tutorials/generate-consume-asynchronous-stream.md
 - name: Tutorials
   items:
-  - name: Overview
-    displayName: tutorials
-    href: tutorials/index.md
   - name: Introduction to classes
     href: tutorials/intro-to-csharp/introduction-to-classes.md
   - name: Object-Oriented programming
     href: tutorials/intro-to-csharp/object-oriented-programming.md
-  - name: Explore record types
-    href: tutorials/exploration/records.md
-  - name: Explore top level statements
-    href: tutorials/exploration/top-level-statements.md
-  - name: Explore patterns in objects
-    href: tutorials/exploration/patterns-objects.md
   - name: Explore string interpolation - interactive
     href: tutorials/exploration/interpolated-strings.yml
   - name: Explore string interpolation - in your environment
     href: tutorials/exploration/interpolated-strings-local.md
   - name: Advanced scenarios for string Interpolation
     href: tutorials/string-interpolation.md
-  - name: Safely update interfaces with default interface methods
-    href: tutorials/default-interface-methods-versions.md
-  - name: Create mixin functionality with default interface methods
-    href: tutorials/mixins-with-default-interface-methods.md
-  - name: Explore indexes and ranges
-    href: tutorials/ranges-indexes.md
-  - name: Work with nullable reference types
-    href: tutorials/nullable-reference-types.md
-  - name: Upgrade an app to nullable reference types
-    href: tutorials/upgrade-to-nullable-references.md
-  - name: Generate and consume asynchronous streams
-    href: tutorials/generate-consume-asynchronous-stream.md
-  - name: Build data-driven algorithms with pattern matching
-    href: tutorials/pattern-matching.md
   - name: Console Application
     href: tutorials/console-teleprompter.md
   - name: REST Client
@@ -80,23 +94,8 @@ items:
     href: tutorials/working-with-linq.md
   - name: Use Attributes
     href: tutorials/attributes.md
-- name: What's new in C#
-  items:
-  - name: C# 9.0
-    displayName: what's new
-    href: whats-new/csharp-9.md
-  - name: C# 8.0
-    href: whats-new/csharp-8.md
-  - name: C# 7.0-7.3
-    href: whats-new/csharp-7.md
-  - name: Breaking changes in the compiler
-    href: whats-new/breaking-changes.md
-  - name: C# Version History
-    href: whats-new/csharp-version-history.md
-  - name: Relationships between language and framework
-    href: whats-new/relationships-between-language-and-library.md
-  - name: Version and update considerations
-    href: whats-new/version-update-considerations.md
+  - name: Build data-driven algorithms with pattern matching
+    href: tutorials/pattern-matching.md
 - name: C# concepts
   items:
   - name: C# type system