WIP: Inline documentation improvements

A raft of inline documentation improvements aimed at helping end users
more easily configure their cloud.  As part of this
commit I removed some variables from scenario-specific files that
are unlikely to actually need to be different than what is set
in user.common.yaml.  This should make things a bit less confusing
to the end user.

Partial-Bug: #1270381

Please feel free to add more commits to augment or correct anything I got wrong!  We'll rebase and then squash the history before merging.