Clean-up Chrome Apps codelab.

chrome/common/extensions/docs/templates/articles/app_codelab_intro.html

 <h1>Build a Todo Chrome App</h1>
 
 <p>Welcome to the Chrome Apps codelab.</p>
 
 <p>Follow along with each step to learn about the basic building blocks of the Chrome Apps platform. By the end of this codelab, you will have an offline-enabled and feature-rich Todo app that you can install on <!-- both --> your desktop computer.<!-- and mobile device. --></p>
 
 <figure>
   <img src="{{static}}/images/app_codelab/chrome-apps-finished-project.png">
   <figcaption>The finished Todo app can be <a href="http://goo.gl/qNNUX">installed from the Chrome Web Store</a>.</figcaption>
 </figure>
 
 <p>Along the way, you will learn:</p>
 
 <ul>
   <li>How to create, run, and debug a Chrome App in <a href="app_codelab_basics.html">Step 1</a>.</li>
-  <li>How to update an existing web app as a Chrome App, deal with common Content Security Policy issues, and adding local storage support in <a href="app_codelab_todomvc.html">Step 2</a>.</li>
+  <li>How to update an existing web app as a Chrome App, deal with Content Security Policy issues, and add local storage support in <a href="app_codelab_todomvc.html">Step 2</a>.</li>
   <li>How to implement alarms and notifications in <a href="app_codelab_alarms.html">Step 3</a>.</li>
   <li>How to display web pages inline in <a href="app_codelab_webview.html">Step 4</a>.</li>
   <li>How to load resources (like images) from external sources in <a href="app_codelab_images.html">Step 5</a>.</li>
   <li>How to write to a file in the native filesystem in <a href="app_codelab_filesystem.html">Step 6</a>.</li>
   <li>How to publish your app to the Chrome Web Store in <a href="app_codelab_publish.html">Step 7</a>.</li>
   <!-- <li>How to run your app on a mobile device as a native Android or iOS app in <a href="app_codelab_mobile.html">Step 8</a>.</li> -->
 </ul>
 
 <p>To prepare for this codelab:</p>
 
 <ul>
   <li>Use the latest version of <a href="https://www.google.com/intl/en/chrome/browser/">Google Chrome</a>.</li>
   <li>Start fresh in an empty project directory on your development computer.</li>
   <li><a href="https://github.com/mangini/io13-codelab/archive/master.zip">Download the reference code</a> for all steps or <a href="https://github.com/mangini/io13-codelab/tree/master/cheat_code">view them on Github</a> in case you get stuck.</li>
 </ul>
 
-<p>Each step builds on top of the previous but, if you decide to skip a step, solutions for every step can be found in the reference code.</p>
+<p>Each step builds on top of the previous.
+You can skip any step and use previous step solutions in the reference code.</p>
 
 <p>Let's get started. Go to <a href="app_codelab_basics.html">Step 1 - Create and run a Chrome App &raquo;</a></p>