Add a note to educate on keystone's two ports
Add a note to educate on keystone's two ports

As suggested by Dung K Hoang, readers find the use of two different
ports in keystone confusing. This patch adds a short explanatory note

Change-Id: I17bccf993f6dc12c1e2a1f9099fbddf53dd1b202
Closes-Bug: 1384970

AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,Akasurde/openstack-manuals,openstack/openstack-manuals,gongysh2004/openstack-manual,saeki-masaki/openstack-manuals,potsmaster/openstack-manuals,openstack/openstack-manuals,kairoaraujo/openstack-manuals,kairoaraujo/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,saeki-masaki/openstack-manuals,openstack/openstack-manuals,Akasurde/openstack-manuals,gongysh2004/openstack-manual,potsmaster/openstack-manuals