Add release notes for Ocata 6.0.0
Add release notes for Ocata 6.0.0

Change-Id: I0d56dfe012d97e8f7206e8777c1b72a6797c328d

openstack/tripleo-heat-templates,dprince/tripleo-heat-templates,dprince/tripleo-heat-templates,openstack/tripleo-heat-templates