add README.md for git hooks

Author: funbringer

hooks/README.md

@@ -0,0 +1,7 @@
+### What's this?
+
+This is a set of git hooks to be executed on special events, e.g. before you commit your changes. To install them, just execute the `install.sh` script, and you're good to go!
+
+### What do they do?
+
+Currently there's only one hook (`pre-commit`) which formats changed python files with `yapf`.