bpo-46120: State that `|` is preferred over `Union` (GH-30222)

Co-authored-by: Éric <merwok@netwok.org>
Co-authored-by: Guido van Rossum <gvanrossum@gmail.com>

Doc/library/typing.rst

@@ -625,7 +625,7 @@ These can be used as types in annotations using ``[]``, each having a unique syn
 
    Union type; ``Union[X, Y]`` is equivalent to ``X | Y`` and means either X or Y.
 
-   To define a union, use e.g. ``Union[int, str]`` or the shorthand ``int | str``.  Details:
+   To define a union, use e.g. ``Union[int, str]`` or the shorthand ``int | str``. Using that shorthand is recommended. Details:
 
    * The arguments must be types and there must be at least one.
 

Misc/NEWS.d/next/Documentation/2021-12-21-12-45-57.bpo-46120.PE0DmJ.rst

+State that ``|`` is preferred for readability over ``Union`` in the :mod:`typing` docs.