Add docs/README.rst

This is just a simple "readme" that directs new readers to the
documentation that will likely be most relevant to them.
Signed-off-by: NMichael Lustfield <michael@lustfield.net>

docs/README.rst

+DAK Documentation
+=================
+
+Most documentation about DAK is available from this directory.
+
+These documents are geared toward getting familiar with DAK:
+
+- ``first.rst`` - Notes and available commands
+- ``development.rst`` - Basic "how to get started with dev"
+- ``TODO`` - Simple list of potential improvements
+- ``database.dia`` - A diagram of the database schema