Updated Logger.log() docstring to clarify that lvl parameter should be an integer.

Lib/logging/__init__.py

@@ -967,7 +967,7 @@ class Logger(Filterer):
 
     def log(self, level, msg, *args, **kwargs):
         """
-        Log 'msg % args' with the severity 'level'.
+        Log 'msg % args' with the integer severity 'level'.
 
         To pass exception information, use the keyword argument exc_info with
         a true value, e.g.