[doc] Leverage the fact that the actual types can now be indexed for typing (GH-22340)



This shows users that they can use the actual types. Using deprecated types is confusing.

This also prefers colections.abc.Sized instead of the alias typing.Sized. I guess the aliases were created to make it convenient to import all collections related types from the same place.

This should be backported to 3.9.

Automerge-Triggered-By: @gvanrossum
diff --git a/Doc/glossary.rst b/Doc/glossary.rst
index 7be755e..9fdbdb1 100644
--- a/Doc/glossary.rst
+++ b/Doc/glossary.rst
@@ -1084,19 +1084,15 @@
       Type aliases are useful for simplifying :term:`type hints <type hint>`.
       For example::
 
-         from typing import List, Tuple
-
          def remove_gray_shades(
-                 colors: List[Tuple[int, int, int]]) -> List[Tuple[int, int, int]]:
+                 colors: list[tuple[int, int, int]]) -> list[tuple[int, int, int]]:
              pass
 
       could be made more readable like this::
 
-         from typing import List, Tuple
+         Color = tuple[int, int, int]
 
-         Color = Tuple[int, int, int]
-
-         def remove_gray_shades(colors: List[Color]) -> List[Color]:
+         def remove_gray_shades(colors: list[Color]) -> list[Color]:
              pass
 
       See :mod:`typing` and :pep:`484`, which describe this functionality.