Removing references to legacy packaged apps across extension docs.

chrome/common/extensions/docs/server2/templates/articles/docs.html

 <h1>Hello There!</h1>
 
 <p>
-This documentation tells you how to write extensions
-and packaged apps for the
+This documentation tells you how to write extensions for the
 <a href="http://www.google.com/chrome">Google Chrome browser</a>.
-Because extensions came first,
-the APIs and these docs say <em>extension</em> everywhere.
 </p>
 
-<p class="caution">
-<b>Note:</b>
-Unless you see a note
-describing an exception for packaged apps,
-everything in this documentation applies to both extensions and packaged apps.
-</p>
-
-
 <h2 id="readme"> Where to start </h2>
 
 <p>
 Before you code,
 read these:
 </p>
 
 <dl>
   <dt> <a href="getstarted.html">Getting Started (Hello, World!)</a> </dt>
   <dd> Build a simple "Hello, World" extension in about 5 minutes </dd>
@@ skipping 107 matching lines @@
       but haven't been integrated into it yet.
 
       <p>
       <strong>Note:</strong>
       The trunk version of the doc is preliminary and might have errors.
       </p>
     </td>
   </tr>
 </table>
 </p>