doc/mgr/orchestrator: update cephadm shell proposed alias entry

doc/mgr/orchestrator: update cephadm shell proposed alias entry

prior change i get following error when using alias as "ceph -v":
INFO:cephadm:Inferring fsid ecfdb924-7341-11ea-943c-020100010027
INFO:cephadm:Using recent ceph image ceph/ceph:v15
/usr/bin/docker: Error response from daemon: OCI runtime create failed: container_linux.go:349: starting container process caused "exec: "/usr/bin/ceph -v": stat /usr/bin/ceph -v: no such file or directory": unknown.
after:
INFO:cephadm:Inferring fsid ecfdb924-7341-11ea-943c-020100010027
INFO:cephadm:Using recent ceph image ceph/ceph:v15
ceph version 15.2.0 (dc6a0b5) octopus (rc)

Signed-off-by: Tobias Fischer <tobias.fischer@clyso.com>