Add gauge.

site/index.html

@@ -498,5 +498,18 @@ let g:gundo_right = 1
                 with a lot of help from others.
             </footer>
         </div>
+        <script type="text/javascript">
+            var _gauges = _gauges || [];
+            (function() {
+             var t   = document.createElement('script');
+             t.type  = 'text/javascript';
+             t.async = true;
+             t.id    = 'gauges-tracker';
+             t.setAttribute('data-site-id', '4f843f8c613f5d65280000e6');
+             t.src = '//secure.gaug.es/track.js';
+             var s = document.getElementsByTagName('script')[0];
+             s.parentNode.insertBefore(t, s);
+             })();
+         </script>
     </body>
 </html>