The Cinder v3 API was marked CURRENT in Mitaka, but there no API ref
was ever created. This is problematic for end users and would hinder
the v3 API from being included in DefCore Interoperability Guidelines
somewhere down the line (since one of DefCore's Criteria[1] is that a
Capability be well documented). This patch creates an API ref for v3.
It also adds a header to the v2 index to show that it is SUPPORTED,
whereas v3 is CURRENT.
[1]
http://git.openstack.org/cgit/openstack/defcore/tree/doc/source/process/CoreCriteria.rst#n77
Change-Id: Ia3a8050cd04ad3a487a79d80acf9691feee6182e
Closes-Bug: #1616072