Fix docs build

Author: ilevkivskyi

docs/source/kinds_of_types.rst

@@ -443,7 +443,7 @@ case you should add an explicit ``... | None`` annotation.
    The Python interpreter internally uses the name ``NoneType`` for
    the type of ``None``, but ``None`` is always used in type
    annotations. The latter is shorter and reads better. (``NoneType``
-   is available as :py:data:`types.NoneType` on Python 3.10+, but is
+   is available as :py:class:`types.NoneType` on Python 3.10+, but is
    not exposed at all on earlier versions of Python.)
 
 .. note::