Minor Manila doc change
Minor Manila doc change

Change-Id: I23452f73291456f21651a1d635428fd3cb9a7da1

bswartz/manila,scality/manila,weiting-chen/manila,openstack/manila,openstack/manila,NetApp/manila,NetApp/manila,sajuptpm/manila,bswartz/manila,sajuptpm/manila,redhat-openstack/manila,vponomaryov/manila,vponomaryov/manila,redhat-openstack/manila,scality/manila,weiting-chen/manila,jcsp/manila,jcsp/manila