[Doc] Add Configure Cinder Notifications
[Doc] Add Configure Cinder Notifications

Cinder data model was added in Pike cycle and that needs
configuration in cinder.conf for refreshing the model in
real time.

This patch set adds Add Configure Cinder Notifications section
for explaining the configuration.

Change-Id: I41cc870e2d47c56fd7c9fcdd6f03c95fa939c3f2

openstack/watcher,stackforge/watcher,openstack/watcher,stackforge/watcher