Removed obsolete note in management.get_commands() docstring.

Commit 901c3708fb documented that the
return dict could directly include command modules instead of name
strings, which was true at the time. However, that possibility was
removed in commit 38f1fe3b35.

django/core/management/__init__.py

@@ -65,10 +65,6 @@ def get_commands():
     pairs from this dictionary can then be used in calls to
     load_command_class(app_name, command_name)
 
-    If a specific version of a command must be loaded (e.g., with the
-    startapp command), the instantiated module can be placed in the
-    dictionary in place of the application name.
-
     The dictionary is cached on the first call and reused on subsequent
     calls.
     """