Just to clarify, you could say something along the lines of: "Normally, you enable cinder-backup by including the cinder-backup.yaml environment file from the Heat template collection. However, we're going to merge it with out existing storage-environment.yaml file."
Thanks Dan, good point. I've added a NOTE in the section to this effect:
<quote>
This resource is also defined in `/usr/share/openstack-tripleo-heat-templates/environments/cinder-backup.yaml`, which you can also invoke directly. For the purposes of this document, we are defining this resource in `/home/stack/templates/storage-environment.yaml` instead, as doing so centralizes all resources and parameters to one environment file.
</quote>