Updated README script tag to latest Angular version

Author: jwngr

README.md

@@ -18,7 +18,7 @@ In order to use AngularFire in your project, you need to include the following f
 
 ```html
 <!-- AngularJS -->
-<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.7/angular.min.js"></script>
+<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.8/angular.min.js"></script>
 
 <!-- Firebase -->
 <script src="https://cdn.firebase.com/js/client/2.1.0/firebase.js"></script>