Document configure option and add to whatsnew

Author: stefanor

Doc/using/configure.rst

@@ -473,6 +473,15 @@ General Options
 
    .. versionadded:: 3.15
 
+.. option:: --with-build-details-suffix=[yes|SUFFIX]
+
+   Rename ``build-details.json`` to permit multiple co-located Python
+   installs. If a custom ``SUFFIX`` is supplied it is used verbatim,
+   otherwise one will be generated from the ``MULTIARCH`` tag with
+   ``-free-threading`` and ``-debug``, as appropriate.
+
+   .. versionadded:: 3.16
+
 
 C compiler options
 ------------------

Doc/whatsnew/3.16.rst

@@ -219,6 +219,12 @@ Build changes
 
   .. _libmpdec: https://www.bytereef.org/mpdecimal/
 
+* Add a :option:`--with-build-details-suffix` configure flag to allow
+  Linux distributions that co-install multiple versions of Python in the
+  same tree to avoid ``build-details.json`` clashes.
+
+  (Contributed by Stefano Rivera in :gh:`131372`.)
+
 
 C API changes
 =============

Misc/NEWS.d/next/Build/2026-05-19-12-45-23.gh-issue-131372.oJykeB.rst

@@ -1,3 +1,3 @@
-Add a ``--with-build-details-suffix=`` configure flag to allow Linux
+Add a :option:`--with-build-details-suffix` configure flag to allow Linux
 distributions that co-install multiple versions of Python in the same tree
 to avoid ``build-details.json`` clashes.