pythongh-136145: Define 'standard library' and 'stdlib' in the glossary (pythonGH-136146)

---------
(cherry picked from commit 92f392a)

Co-authored-by: Zachary Ware <zach@python.org>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Co-authored-by: Éric <merwok@netwok.org>

Author: 3 people

Doc/glossary.rst

@@ -1235,6 +1235,16 @@ Glossary
       and ending with double underscores.  Special methods are documented in
       :ref:`specialnames`.
 
+   standard library
+      The collection of :term:`packages <package>`, :term:`modules <module>`
+      and :term:`extension modules <extension module>` distributed as a part
+      of the official Python interpreter package.  The exact membership of the
+      collection may vary based on platform, available system libraries, or
+      other criteria.  Documentation can be found at :ref:`library-index`.
+
+      See also :data:`sys.stdlib_module_names` for a list of all possible
+      standard library module names.
+
    statement
       A statement is part of a suite (a "block" of code).  A statement is either
       an :term:`expression` or one of several constructs with a keyword, such
@@ -1245,6 +1255,9 @@ Glossary
       issues such as incorrect types. See also :term:`type hints <type hint>`
       and the :mod:`typing` module.
 
+   stdlib
+      An abbreviation of :term:`standard library`.
+
    strong reference
       In Python's C API, a strong reference is a reference to an object
       which is owned by the code holding the reference.  The strong