Add an example of restricting the launch command

docs/remote-control.rst

@@ -245,7 +245,18 @@ as shown below:
         # effect on the command.
 
         # The command payload will vary from command to command, see
-       # the rc protocol docs for details.
+        # the rc protocol docs for details. Below is an example of
+        # restricting the launch command to allow only running the
+        # default shell.
+
+        if cmd_name != 'launch':
+            return None
+        if cmd_payload.get('args') or cmd_payload.get('env') or cmd_payload.get('copy_cmdline') or cmd_payload.get('copy_env'):
+            return False
+        # prints in this function go to the parent kitty process STDOUT
+        print('Allowing launch command:', cmd_payload)
+        return True
+
 
 .. _rc_mapping: