gh-102873: logging.LogRecord docs: improve description of msg parameter (#102875)

Co-authored-by: Alex Waygood <[email protected]>

Author: aminalaee

Doc/library/logging.rst

@@ -813,8 +813,9 @@ wire).
    :type lineno: int
 
    :param msg: The event description message,
-      which can be a %-format string with placeholders for variable data.
-   :type msg: str
+      which can be a %-format string with placeholders for variable data,
+      or an arbitrary object (see :ref:`arbitrary-object-messages`).
+   :type msg: typing.Any
 
    :param args: Variable data to merge into the *msg* argument
       to obtain the event description.