bpo-41203: Replace Mac OS X and OS X with macOS (GH-28515) (GH-28523)

Replace old names when they refer to actual versions of macOS.
Keep historical names in references to older versions.

Co-authored-by: Patrick Reader <_@pxeger.com>
(cherry picked from commit 36122e18148c5b6c78ebce1d36d514fd7cf250f5)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
diff --git a/Doc/library/urllib.request.rst b/Doc/library/urllib.request.rst
index dbb8c25..659a363 100644
--- a/Doc/library/urllib.request.rst
+++ b/Doc/library/urllib.request.rst
@@ -169,8 +169,8 @@
    This helper function returns a dictionary of scheme to proxy server URL
    mappings. It scans the environment for variables named ``<scheme>_proxy``,
    in a case insensitive approach, for all operating systems first, and when it
-   cannot find it, looks for proxy information from Mac OSX System
-   Configuration for Mac OS X and Windows Systems Registry for Windows.
+   cannot find it, looks for proxy information from System
+   Configuration for macOS and Windows Systems Registry for Windows.
    If both lowercase and uppercase environment variables exist (and disagree),
    lowercase is preferred.
 
@@ -303,8 +303,8 @@
    the list of proxies from the environment variables
    ``<protocol>_proxy``.  If no proxy environment variables are set, then
    in a Windows environment proxy settings are obtained from the registry's
-   Internet Settings section, and in a Mac OS X environment proxy information
-   is retrieved from the OS X System Configuration Framework.
+   Internet Settings section, and in a macOS environment proxy information
+   is retrieved from the System Configuration Framework.
 
    To disable autodetected proxy pass an empty dictionary.