[3.11] Fix the confusing "User-defined methods" reference in the data…

…model (pythonGH-114276) (python#114366)

Doc/reference/datamodel.rst

@@ -1507,7 +1507,7 @@ Class method objects
 A class method object, like a static method object, is a wrapper around another
 object that alters the way in which that object is retrieved from classes and
 class instances. The behaviour of class method objects upon such retrieval is
-described above, under "User-defined methods". Class method objects are created
+described above, under :ref:`"instance methods" <instance-methods>`. Class method objects are created
 by the built-in :func:`classmethod` constructor.