Bug 1997964

* Description of problem:

When we try to add a host and if it fails, then we display an output similar to :

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[ceph: root@vm501 /]# ceph orch host add vm502
Error EINVAL: Cannot resolve ip for host vm502: [Errno -2] Name or service not known
You may need to supply an address for vm502

Please make sure that the host is reachable and accepts connections using the cephadm SSH key
To add the cephadm SSH key to the host:
> ceph cephadm get-pub-key > ~/ceph.pub
> ssh-copy-id -f -i ~/ceph.pub root@vm502


*********
To check that the host is reachable open a new shell with the --no-hosts flag:
> cephadm shell --no-hosts
*********

Then run the following:
> ceph cephadm get-ssh-config > ssh_config
> ceph config-key get mgr/cephadm/ssh_identity_key > ~/cephadm_private_key
> chmod 0600 ~/cephadm_private_key
> ssh -F ssh_config -i ~/cephadm_private_key root@vm502
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On running #cephadm shell --no-hosts it gives :
cephadm: error: unrecognized arguments: --no-hosts


Is this argument not available? If no, then we need to correct the output message to include the correct argument. 



* Version-Release number of selected component (if applicable):
RHCS 5

* How reproducible:
Always

* Steps to Reproduce:
1. Try to add a host which will result in failing
2. The error message displays to run  #cephadm shell --no-hosts
3. Running  #cephadm shell --no-hosts would show unrecognized arguments: --no-hosts