update whatsnew entry

Author: sayandipdutta

Doc/whatsnew/3.14.rst

@@ -310,6 +310,10 @@ functools
   to reserve a place for positional arguments.
   (Contributed by Dominykas Grigonis in :gh:`119127`.)
 
+* Allow the *initial* parameter of :func:`functools.reduce` to be passed
+  as a keyword argument.
+  (Contributed by Sayandip Dutta in :gh:`125916`.)
+
 
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