Add a link to the download archives (#167)

Author: AA-Turner

templates/404.html

@@ -65,7 +65,9 @@ <h3>Navigation</h3>
         <div class="body" role="main">
           <h1>404 — Archive Not Found</h1>
           <p>The archive you're trying to download has not been built yet.</p>
-          <p>Please try again later.</p>
+            <p>Please try again later or consult the
+              <a href="https://docs.python.org/3/archives/">archives for earlier versions</a>.
+            </p>
           <div class="clearer"></div>
         </div>
       </div>