keystone-paste.ini docs for deployers are out of date
keystone-paste.ini docs for deployers are out of date

Updated the docs to better reflect v3 deployments. Essentially, matched
the [app:service_v3] entry with the value in the ini file.

Closes-Bug: 1504891
Change-Id: I57f6a2a5287b2f6aa108586c1ad07b9a6235d53d

ilay09/keystone,ilay09/keystone,openstack/keystone,ajayaa/keystone,ilay09/keystone,maestro-hybrid-cloud/keystone,himanshu-setia/keystone,openstack/keystone,cernops/keystone,mahak/keystone,rajalokan/keystone,maestro-hybrid-cloud/keystone,klmitch/keystone,ajayaa/keystone,himanshu-setia/keystone,dims/keystone,mahak/keystone,klmitch/keystone,cernops/keystone,rajalokan/keystone,mahak/keystone,rajalokan/keystone,dims/keystone,openstack/keystone