Add note for v3 API clients using auth plugin docs
Add note for v3 API clients using auth plugin docs

Change-Id: I3d07c3f27ac38f9ead0481271460b3b3633b8c1d
Closes-Bug: #1311324

himanshu-setia/keystone,rajalokan/keystone,reeshupatel/demo,vivekdhayaal/keystone,promptworks/keystone,mahak/keystone,UTSA-ICS/keystone-kerberos,dstanek/keystone,rodrigods/keystone,jamielennox/keystone,openstack/keystone,rajalokan/keystone,klmitch/keystone,UTSA-ICS/keystone-kerberos,ajayaa/keystone,MaheshIBM/keystone,mahak/keystone,nuxeh/keystone,klmitch/keystone,openstack/keystone,roopali8/keystone,reeshupatel/demo,takeshineshiro/keystone,maestro-hybrid-cloud/keystone,ilay09/keystone,jamielennox/keystone,ilay09/keystone,rajalokan/keystone,ging/keystone,maestro-hybrid-cloud/keystone,reeshupatel/demo,blueboxgroup/keystone,ilay09/keystone,idjaw/keystone,vivekdhayaal/keystone,mahak/keystone,rushiagr/keystone,vivekdhayaal/keystone,himanshu-setia/keystone,idjaw/keystone,ging/keystone,rushiagr/keystone,MaheshIBM/keystone,rushiagr/keystone,dims/keystone,jumpstarter-io/keystone,jumpstarter-io/keystone,jonnary/keystone,dstanek/keystone,jonnary/keystone,nuxeh/keystone,rodrigods/keystone,promptworks/keystone,cernops/keystone,jumpstarter-io/keystone,takeshineshiro/keystone,dims/keystone,promptworks/keystone,dstanek/keystone,openstack/keystone,roopali8/keystone,nuxeh/keystone,ajayaa/keystone,cernops/keystone,blueboxgroup/keystone