[config-ref] Remove keystone domain-specific configuration file content
[config-ref] Remove keystone domain-specific configuration file content

Remove information on domain-specific configuration file options per bug

Change-Id: I0a6bb0f522f7dc4ca71a4c61f84a063f6a398a48
Closes-Bug: #1493913

openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals