Remove extra cloud-admin in URL of End User Guide

This changes:
http://docs.openstack.org/cloud-admin/user-guide-admin/content/ to
http://docs.openstack.org/user-guide-admin/content/

Change-Id: I508c1983ca8d577e8fab45051b3d8bacd2d8865f
Merge "Remove extra cloud-admin in URL of End User Guide"