This fix adds the detailed API reference to the developers guide
as it's done in major projects in the stack.
It also fix Sphinx warning and errors and adds a .rst files
generator to easily update the api reference in the future.
Plus, it includes an index for API, modules and search.
Co-Authored-By: Flavio Percoco <fpercoco@redhat.com>
Change-Id: If42121c9e8e852785cb2db3aa5d6895223b9d604