Fix CLI docs typo (#19426)

Author: carmocca

docs/source-pytorch/cli/lightning_cli_advanced.rst

@@ -86,7 +86,7 @@ save the config in a logger. An example of this is:
 
 .. note::
 
-    The ``save_config``method is only called on rank zero. This allows to implement a custom save config without having
+    The ``save_config`` method is only called on rank zero. This allows to implement a custom save config without having
     to worry about ranks or race conditions. Since it only runs on rank zero, any collective call will make the process
     hang waiting for a broadcast. If you need to make collective calls, implement the ``setup`` method instead.