bpo-29888: Fix the link referring to the "Python download page" (GH-824)

Doc/tools/templates/download.html

@@ -42,7 +42,7 @@ in the table are the size of the download files in megabytes.</p>
 <p>These archives contain all the content in the documentation.</p>
 
 <p>HTML Help (<tt>.chm</tt>) files are made available in the "Windows" section
-on the <a href="https://www.python.org/download/releases/{{ release[:5] }}/">Python
+on the <a href="https://www.python.org/downloads/release/python-{{ release.replace('.', '') }}/">Python
 download page</a>.</p>