Update the help str of keystone opts
Update the help str of keystone opts

Change-Id: Ibe1715929c045652d49526867495f645b931c515

midonet/kuryr,celebdor/kuryr-libnetwork,celebdor/kuryr,celebdor/kuryr-libnetwork,midonet/kuryr,openstack/kuryr,celebdor/kuryr,midonet/kuryr,celebdor/kuryr-libnetwork,openstack/kuryr