Fix #1801 - Add documentation for disabling hash based routing.

index.html

@@ -2084,6 +2084,8 @@ app.navigate("help/troubleshooting", {trigger: true, replace: true});
     <p>
       To indicate that you'd like to use HTML5 <tt>pushState</tt> support in
       your application, use <tt>Backbone.history.start({pushState: true})</tt>.
+      Hash based routing can be disabled by using <tt>{hashChange: false}</tt>,
+      which can be useful when pre-rendering content server side.
     </p>
 
     <p>