Goal: 

Before FR5 we described how to enable notifications in the official persistent storage guide [1].
We should update the sections for cinder/glance/manila to reflect the new messagingBus/notificationsBus interface introduced for FR5.

[1] https://docs.redhat.com/en/documentation/red_hat_openstack_services_on_openshift/18.0/html-single/customizing_persistent_storage/index#proc_enabling-volume-notifications_customizing-cinder