pythonGH-123299: Announce final release in What's New in Python 3.14 (python#139631)

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Author: AA-Turner

Doc/whatsnew/3.13.rst

@@ -60,7 +60,7 @@ Summary -- Release Highlights
 .. This section singles out the most important changes in Python 3.13.
    Brevity is key.
 
-Python 3.13 is the latest stable release of the Python programming
+Python 3.13 is a stable release of the Python programming
 language, with a mix of changes to the language, the implementation
 and the standard library.
 The biggest changes include a new `interactive interpreter

Doc/whatsnew/3.14.rst

@@ -46,7 +46,7 @@
    when researching a change.
 
 This article explains the new features in Python 3.14, compared to 3.13.
-Python 3.14 will be released on 7 October 2025.
+Python 3.14 was released on 7 October 2025.
 For full details, see the :ref:`changelog <changelog>`.
 
 .. seealso::
@@ -60,7 +60,7 @@ Summary -- Release highlights
 .. This section singles out the most important changes in Python 3.14.
    Brevity is key.
 
-Python 3.14 will be the latest stable release of the Python programming
+Python 3.14 is the latest stable release of the Python programming
 language, with a mix of changes to the language, the implementation,
 and the standard library.
 The biggest changes include :ref:`template string literals
@@ -3083,7 +3083,7 @@ Deprecated C APIs
 
 .. _whatsnew314-build-changes:
 
-Build Changes
+Build changes
 =============
 
 * :pep:`776`: Emscripten is now an officially supported platform at