Update the Nova CLI docoder document
Update the Nova CLI docoder document

There are several update in CLI decoder document.
- Change flavor set/unset to flavor set/unset --property
- Update the mapping with flavor-update, interface-attach, and interface-detach

Change-Id: I1db50188b3643d3fe28689dc73b3f63806defd29

openstack/python-openstackclient,openstack/python-openstackclient