3.6 what's new: fix a reference to PEP 528 (GH-7113) (#7256)

(cherry picked from commit 495e567a2b3bbe3b99f0c253edf12997a9ff4ee1)

Co-authored-by: Dmitry Shachnev <mitya57@users.noreply.github.com>
diff --git a/Doc/whatsnew/3.6.rst b/Doc/whatsnew/3.6.rst
index cb8c53a..ed489c1 100644
--- a/Doc/whatsnew/3.6.rst
+++ b/Doc/whatsnew/3.6.rst
@@ -148,7 +148,7 @@
 
 Windows improvements:
 
-* :ref:`PEP 528 <whatsnew36-pep529>` and :ref:`PEP 529 <whatsnew36-pep529>`,
+* :ref:`PEP 528 <whatsnew36-pep528>` and :ref:`PEP 529 <whatsnew36-pep529>`,
   Windows filesystem and console encoding changed to UTF-8.
 
 * The ``py.exe`` launcher, when used interactively, no longer prefers