[3.14] Docs: Add a diagram of pathlib path components (GH-159727) (#159874)

Co-authored-by: Paul Ganssle <1377457+pganssle@users.noreply.github.com>

Author: miss-islington

Doc/library/pathlib-parts.svg

@@ -307,6 +307,21 @@ Methods and properties
 
    from pathlib import PurePath, PurePosixPath, PureWindowsPath
 
+The :attr:`~PurePath.parent`, :attr:`~PurePath.name`,
+:attr:`~PurePath.stem`, and :attr:`~PurePath.suffix` properties describe
+different parts of a path.  For example, given::
+
+   >>> p = PurePosixPath('/srv/holy/grail.tar.gz')
+
+.. image:: pathlib-parts.svg
+   :align: center
+   :class: invert-in-dark-mode
+   :alt: For p = PurePosixPath('/srv/holy/grail.tar.gz'), p.parent is
+         PurePosixPath('/srv/holy'), p.name is 'grail.tar.gz',
+         p.stem is 'grail.tar', and p.suffix is '.gz'.
+
+The stem excludes only the final suffix: in this example, it includes ``.tar``.
+
 Pure paths provide the following methods and properties:
 
 .. attribute:: PurePath.parser