doc: development-process: convert it to ReST markup

This document is on good shape for ReST: all it was needed was
to fix the section markups, add a toctree, convert the tables
and add a few code/quote blocks.

While not strictly required, I opted to use lowercase for
the titles, just like the other books that were converted
to Sphinx.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>