Descriptions of pause and resume actions can be improved

The descriptions for the 'pause' and 'resume' actions can be improved:

pause Pause keystone services.
If the keystone deployment is clustered using the hacluster charm, the
corresponding hacluster unit on the node must first be paused as well.
Not doing so may lead to an interruption of service.

resume Resume keystone services.
If the keystone deployment is clustered using the hacluster charm, the
corresponding hacluster unit on the node must be resumed as well.

Consider the following (which I will use as a model for all other bugs I intend to raise on this topic):

pause Pause the Keystone service. If Keystone is clustered using the hacluster charm, first pause the hacluster unit and then pause the keystone unit.
resume Resume the Keystone service. If Keystone is clustered using the hacluster charm, first resume the keystone unit and then resume the hacluster unit.