[3.12] gh-115821: [Enum] better error message for calling super().__new__() (GH-116065)

Add note to not call super().__new__() in docs.

Author: ethanfurman

Doc/library/enum.rst

@@ -390,6 +390,9 @@ Data Types
 
       results in the call ``int('1a', 16)`` and a value of ``17`` for the member.
 
+      ..note:: When writing a custom ``__new__``, do not use ``super().__new__`` --
+               call the appropriate ``__new__`` instead.
+
    .. method:: Enum.__repr__(self)
 
       Returns the string used for *repr()* calls.  By default, returns the