doc/rados: add stop monitor command

Add the command for stopping a monitor to the procedure that explains
how to inject a monmap into a monitor.

Zac of the future: cf. 05 Aug 2023.

Signed-off-by: Zac Dover <[email protected]>

Author: zdover23

doc/rados/troubleshooting/troubleshooting-mon.rst

@@ -388,7 +388,11 @@ B. **Inject a monmap into the monitor.**
 
           In this example, the ID of the stopped Monitor is ``ID-FOO``.
 
-    #. Stop the Monitor into which the ``monmap`` will be injected. 
+    #. Stop the Monitor into which the ``monmap`` will be injected:
+
+       .. prompt:: bash 
+
+          service ceph -a stop mon.{mon-id}
 
     #. Inject the monmap into the stopped Monitor: