monmaptool: document the new --addv argument
Since the introduction of the new Messenger v2 protocol in Ceph Nautilus the
monmaptool has been updated to support a new
--addv argument enabling the user to specify monitor endpoints using the new "bracketed list" style that supports specifying the protocol version as well as specifying multiple addresses at once (as in http://docs.ceph.com/docs/master/rados/configuration/msgr2/#address-formats).
Even if such functionality is present in
monmaptool it is not documented at all, not in the tool itself (
monmaptool --help) nor in the man page.
To clarify not only such functionality's behavior but also if it should be considered stable to use please add the relevant sections in the documentation.