Add option to switch back to SSH REX mode

BZ: https://bugzilla.redhat.com/show_bug.cgi?id=2269398

guides/common/modules/con_transport-modes-for-remote-execution.adoc

@@ -9,6 +9,16 @@ The SSH service must be enabled and active on the target hosts.
 The remote execution {SmartProxy} must have access to the SSH port on the target hosts.
 Unless you have a different setting, the standard SSH port is 22.
 
+[NOTE]
+====
+If your {SmartProxy} already uses the `pull-mqtt` mode and you want to switch back to the `ssh` mode, run this `{foreman-installer}` command:
+
+[options="nowrap",subs="+quotes,verbatim,attributes"]
+----
+# {foreman-installer} --foreman-proxy-plugin-remote-execution-script-mode=ssh
+----
+====
+
 On {SmartProxies} in `pull-mqtt` mode, remote execution uses Message Queueing Telemetry Transport (MQTT) to publish jobs it receives from {ProjectServer}.
 The host subscribes to the MQTT broker on {SmartProxy} for job notifications using the `yggdrasil` pull client.
 After the host receives a notification, it pulls job details from {SmartProxy} over HTTPS, runs the job, and reports results back to {SmartProxy}.