Change inline docs about class fake storage variable
Change inline docs about class fake storage variable

Adjust the docs to better describe why a fake storage
class attribute exists and how it is used and what it
represents compared to a real zookeeper setup.

Change-Id: I255ccd83c8033266e9cee09a343468ae4e0f2bfd

citrix-openstack-build/tooz,citrix-openstack-build/tooz,openstack/tooz,openstack/tooz