fix most sphinx warnings (1.4)

fix most sphinx warnings (1.4)

still can't figure out the warnings with some of the older
changelog files.

this cherry-picks the sphinx fixes from 1.4 and additionally
fixes a small number of new issues in the 2.0 docs. However,
2.0 has many more errors to fix, primarily from the removal
of the legacy tutorials left behind a lot of labels that need
to be re-linked to the new tutorial.

Fixes: #7946
Change-Id: Id657ab23008eed0b133fed65b2f9ea75a626215c
(cherry picked from commit 9b55a423459236ca8a2ced713c9e93999dd18922)