RELEASENOTES: Add operations-guide manila entry
RELEASENOTES: Add operations-guide manila entry

Change-Id: I421f355d43b26e4a95d1ffaefd2d321d270c551f

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