bpo-28556: Remove another mention of metaclass of Generic in typing docs (GH-16743)


Metaclass was removed in Python 3.7 (there is already a `versionchanged` item about this).

https://bugs.python.org/issue28556
(cherry picked from commit 8144095707f87bdee6f3e1bbb15283ea61381be6)

Co-authored-by: Ivan Levkivskyi <levkivskyi@gmail.com>
diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst
index 642f8c6..94d60b4 100644
--- a/Doc/library/typing.rst
+++ b/Doc/library/typing.rst
@@ -231,8 +231,8 @@
 single type parameter ``T`` . This also makes ``T`` valid as a type within the
 class body.
 
-The :class:`Generic` base class uses a metaclass that defines
-:meth:`__getitem__` so that ``LoggedVar[t]`` is valid as a type::
+The :class:`Generic` base class defines :meth:`__class_getitem__` so that
+``LoggedVar[t]`` is valid as a type::
 
    from typing import Iterable