[cli-ref] Update python-cinderclient to 1.6.0
[cli-ref] Update python-cinderclient to 1.6.0

Use Block Storage API v2 first.

Depends-On: Ic7cc5c4165c82756e09cce04d4fffaf2226cf5f3
Change-Id: If0b17ebdf16bae4b28427af922e18edd0803949c

AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals