Removing references to legacy packaged apps across extension docs.

chrome/common/extensions/docs/server2/templates/intros/pageAction.html

 <p>
 Use page actions to put icons inside the address bar.
 Page actions represent actions
 that can be taken on the current page,
 but that aren't applicable to all pages.
 Some examples:
 </p>
 <ul>
   <li> Subscribe to this page's RSS feed </li>
   <li> Make a slideshow out of this page's photos </li>
 </ul>
 
 <p>
 The RSS icon in the following screenshot
 represents a page action
 that lets you subscribe to
 the RSS feed for the current page.
 </p>
 
 <img src="{{static}}/images/page-action.png"
   width="361" height="79" />
 
 <p>
 If you want the extension's icon to always be visible,
 use a <a href="browserAction.html">browser action</a> instead.
 </p>
 
-<p class="caution">
-<strong>Note:</strong>
-Packaged apps cannot use page actions.
-</p>
-
-
 <h2 id="manifest">Manifest</h2>
 
 <p>
 Register your page action in the
 <a href="manifest.html">extension manifest</a>
 like this:
 </p>
 
 <pre>{
   "name": "My extension",
@@ skipping 55 matching lines @@
 
 <h2 id="examples"> Examples </h2>
 
 <p>
 You can find simple examples of using page actions in the
 <a href="http://src.chromium.org/viewvc/chrome/trunk/src/chrome/common/extensions/docs/examples/api/pageAction/">examples/api/pageAction</a>
 directory.
 For other examples and for help in viewing the source code, see
 <a href="samples.html">Samples</a>.
 </p>