Reorganize api-ref: v3-ext simple-cert.inc
Reorganize api-ref: v3-ext simple-cert.inc

Reorganize as per the documentation session at PTG:
https://etherpad.openstack.org/p/queens-ptg-keystone-doc-cleanup

Change-Id: I86849a4e7efbe9117c24636699987a6b475d777b

openstack/keystone,openstack/keystone,openstack/keystone,mahak/keystone,mahak/keystone,mahak/keystone