Removing references to legacy packaged apps across extension docs.

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

 <h1>Override Pages</h1>
 
 
 <style>
 #pics {
   margin:2em 1em 1.5em;
 }
 
 #pics td {
   text-align:center;
@@ skipping 54 matching lines @@
 the Bookmark Manager and History pages.
 </p>
 
 <p>
 Incognito windows are treated specially.
 New Tab pages cannot be overridden in incognito windows.
 Other override pages work in incognito windows
 as long as the
 <a href="manifest.html#incognito">incognito</a>
 manifest property is set to "spanning"
-(which is the default value for extensions
-but not for packaged apps).
+(which is the default value).
 See <a href="overview.html#incognito">Saving data and incognito mode</a>
 in the Overview for more details on how you should treat
 incognito windows.
 </p>
 
 <p>
 The following screenshots show the default New Tab page
 next to a custom New Tab page.
 </p>
 
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     </p>
   </li>
 </ul>
 
 <h2 id="examples"> Examples </h2>
 
 <p>
 See the
 <a href="samples.html#chrome_url_overrides">override samples</a>.
 </p>