ceph: fix a small error in the ceph command help

ceph: fix a small error in the ceph command help

Before:
```
  --cluster CLUSTER     cluster name
  --admin-daemon ADMIN_SOCKET
                        submit admin-socket command (e.g. "help" fora list of
                        available commands)
  -s, --status          show cluster status
```
^ 'fora list' is probably not intentional.

Due to the way the strings were concatenated in the python sources the
words 'for' and 'a' lacked a space between them. Add a space before
'a' and fix the help output.

Signed-off-by: John Mulligan <jmulligan@redhat.com>