docs(tutorial): fix links to bower in Step 11

Minor change: add missing bower reference link.

Closes #7005

Author: yilinglu

docs/content/tutorial/step_11.ngdoc

@@ -263,4 +263,5 @@ learn how to improve this application with animations.
 <ul doc-tutorial-nav="11"></ul>
 
 [restful]: http://en.wikipedia.org/wiki/Representational_State_Transfer
-[jasmine-matchers]: https://github.com/pivotal/jasmine/wiki/Matchers
+[jasmine-matchers]: https://github.com/pivotal/jasmine/wiki/Matchers
+[bower]: http://bower.io/