Add node adoption user guide
Add node adoption user guide

Change-Id: Id250d6fc1d3a154bc97178b6c0e7309c69984056
Depends-On: 25bd7c3bd9a140dc9d21729b476859d6b37780b5

openstack/senlin,openstack/senlin,stackforge/senlin,stackforge/senlin,openstack/senlin