gh-104874: Document NewType.__supertype__ (#104875)

Author: JelleZijlstra

Doc/library/typing.rst

@@ -1648,6 +1648,18 @@ These are not used in annotations. They are building blocks for declaring types.
       UserId = NewType('UserId', int)
       first_user = UserId(1)
 
+   .. attribute:: __module__
+
+      The module in which the new type is defined.
+
+   .. attribute:: __name__
+
+      The name of the new type.
+
+   .. attribute:: __supertype__
+
+      The type that the new type is based on.
+
    .. versionadded:: 3.5.2
 
    .. versionchanged:: 3.10

Misc/NEWS.d/next/Library/2023-05-24-09-34-23.gh-issue-104874.oqyJSy.rst

@@ -0,0 +1,2 @@
+Document the ``__name__`` and ``__supertype__`` attributes of
+:class:`typing.NewType`. Patch by Jelle Zijlstra.