[3.12] Link to PEP sections in What's New in 3.12 (GH-108878) (#108890)

Link to PEP sections in What's New in 3.12 (GH-108878)
(cherry picked from commit 7855d32)

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

Doc/whatsnew/3.12.rst

@@ -68,21 +68,21 @@ Summary -- Release highlights
 
 New grammar features:
 
-* :pep:`701`: Syntactic formalization of f-strings
+* :ref:`whatsnew312-pep701`
 
 Interpreter improvements:
 
 * :ref:`whatsnew312-pep684`
 
 New typing features:
 
-* :pep:`688`: Making the buffer protocol accessible in Python
+* :ref:`whatsnew312-pep688`
 
 * :ref:`whatsnew312-pep692`
 
 * :ref:`whatsnew312-pep695`
 
-* :pep:`698`: Override Decorator for Static Typing
+* :ref:`whatsnew312-pep698`
 
 Important deprecations, removals or restrictions:
 
@@ -268,6 +268,8 @@ Inlining does result in a few visible behavior changes:
 
 Contributed by Carl Meyer and Vladimir Matveev in :pep:`709`.
 
+.. _whatsnew312-pep688:
+
 PEP 688: Making the buffer protocol accessible in Python
 --------------------------------------------------------
 
@@ -341,6 +343,8 @@ See :pep:`692` for more details.
 
 (Contributed by Franek Magiera in :gh:`103629`.)
 
+.. _whatsnew312-pep698:
+
 PEP 698: Override Decorator for Static Typing
 ---------------------------------------------