This fixes several things:
1. The consistencygroup_id and metadata parameters are optional.
2. Several parameters used were for non-volume types, this changes
the api-ref to use the proper parameters that have the correct
descriptions for creating a volume.
At some point the parameter names in parameters.yaml need to have
more descriptive names than the lazy *_1, *_2, etc names so it's
easier to know what a parameter is for,
e.g. volume_description_body_required, but that's for a later
cleanup.
Change-Id: I1fb8ca507c85bfbf0add41b507c014ae995e17d0
Closes-Bug: #1642983
33d1270dca