Update release notes for 1.2.0 and 1.2.1
Update release notes for 1.2.0 and 1.2.1

Prepping for tag.

Change-Id: I8ae5e5a0e7ea140d84a0838ffd2ce0c08fcc6aad

eayunstack/python-cinderclient,scottdangelo/cinderclient-api-microversions,eayunstack/python-cinderclient,scottdangelo/cinderclient-api-microversions