Supporting APIv2 in saharaclient meant that there is now some fancier
inheritance going on, so Sphinx :members: now misses a bunch of
user-facing methods. Now, start using :inherited-members: to get what
we want.
Additionally, put the v2 docs under the main reference section instead
of in their own section.
Change-Id: I56067fe54332497f8d0962986383b74a27d84a76
Closes-Bug: #1745650
ee5f17307a