change "overriden" to "overridden" in two places.

index.html

@@ -2443,7 +2443,7 @@ <h2 id="Sync">Backbone.sync</h2>
     </p>
 
     <p>
-      The <b>sync</b> function may be overriden globally as <tt>Backbone.sync</tt>,
+      The <b>sync</b> function may be overridden globally as <tt>Backbone.sync</tt>,
       or at a finer-grained level, by adding a <tt>sync</tt> function to a Backbone
       collection or to an individual model.
     </p>
@@ -3070,7 +3070,7 @@ <h2 id="faq">F.A.Q.</h2>
       extend and enhance it in the ways you see fit &mdash; the entire source
       code is <a href="docs/backbone.html">annotated</a> to make this easier
       for you. You'll find that there's very little there apart from core
-      functions, and most of those can be overriden or augmented should you find
+      functions, and most of those can be overridden or augmented should you find
       the need. If you catch yourself adding methods to <tt>Backbone.Model.prototype</tt>,
       or creating your own base subclass, don't worry &mdash; that's how things are
       supposed to work.