bpo-31766: restore 3.5 to docs version switchers (#3969)

Doc/tools/static/switchers.js

@@ -12,6 +12,7 @@
   var all_versions = {
     '3.7': 'dev (3.7)',
     '3.6': '3.6',
+    '3.5': '3.5',
     '2.7': '2.7',
   };
 

Doc/tools/templates/indexsidebar.html

@@ -2,8 +2,9 @@
 <p><a href="{{ pathto('download') }}">{% trans %}Download these documents{% endtrans %}</a></p>
 <h3>{% trans %}Docs for other versions{% endtrans %}</h3>
 <ul>
-  <li><a href="https://docs.python.org/2.7/">{% trans %}Python 2.7 (stable){% endtrans %}</a></li>
   <li><a href="https://docs.python.org/3.6/">{% trans %}Python 3.6 (stable){% endtrans %}</a></li>
+  <li><a href="https://docs.python.org/3.5/">{% trans %}Python 3.5 (stable){% endtrans %}</a></li>
+  <li><a href="https://docs.python.org/2.7/">{% trans %}Python 2.7 (stable){% endtrans %}</a></li>
   <li><a href="https://www.python.org/doc/versions/">{% trans %}Old versions{% endtrans %}</a></li>
 </ul>