fix sample config link that 404s
fix sample config link that 404s

this link 404s:
  http://docs.openstack.org/developer/keystone/_static/keystone.conf.sample

it can be seen on this page:
  http://docs.openstack.org/developer/keystone/sample_config.html

Change-Id: Ide97caf90659e3bb3511fd629e945c275e522151

klmitch/keystone,openstack/keystone,rajalokan/keystone,mahak/keystone,rajalokan/keystone,ilay09/keystone,cernops/keystone,openstack/keystone,himanshu-setia/keystone,openstack/keystone,himanshu-setia/keystone,mahak/keystone,klmitch/keystone,mahak/keystone,cernops/keystone,ilay09/keystone,rajalokan/keystone,ilay09/keystone