Doc fixes for RAPI

After moving the documentation from the .py files to .rst, we had some
cleanups to do.

This fixes the formatting of the comments, improves them a little, and
removes deprecated info (DOC_URI) from the python source.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>