Fix the doc url in README
Fix the doc url in README

Change-Id: I1f54e2179366aa8b95d0586650d71620fd99161f

cfarquhar/openstack-ansible,cfarquhar/openstack-ansible,bunchc/openstack-ansible,bunchc/openstack-ansible,stackforge/os-ansible-deployment,stackforge/os-ansible-deployment,openstack/openstack-ansible,openstack/openstack-ansible