Removing references to legacy packaged apps across extension docs.

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

 <h1>Formats: Manifest Files</h1>
 
-
 <p>
 Every extension, installable web app, and theme has a
 <a href="http://www.json.org">JSON</a>-formatted manifest file,
 named <code>manifest.json</code>,
 that provides important information.
 </p>
 
 <h2 id="overview"> Field summary </h2>
 
 <p>
@@ skipping 501 matching lines @@
 <tr>
   <td> "clipboardRead" </td>
   <td> Required if the extension uses
        <code>document.execCommand('paste')</code>. </td>
 </tr>
 <tr>
   <td> "clipboardWrite" </td>
   <td> Indicates the app or extension uses
        <code>document.execCommand('copy')</code> or
        <code>document.execCommand('cut')</code>. This permission is <b>required
-       for hosted apps</b>; it's recommended for extensions and packaged apps.
+       for hosted apps</b>; it's recommended for extensions.
        </td>
 </tr>
 <tr>
   <td> "contentSettings" </td>
   <td> Required if the extension uses the
        <a href="contentSettings.html">chrome.contentSettings</a> module. </td>
 </tr>
 <tr>
   <td> "contextMenus" </td>
   <td> Required if the extension uses the
@@ skipping 368 matching lines @@
 goes into more detail about implementing a sandboxing workflow that enables use
 of libraries that would otherwise have issues executing under extension's
 <a href="../extensions/contentSecurityPolicy.html">default Content Security
 Policy</a>.
 </p>
 
 <p>
 Sandboxed page may only be specified when using
 <a href="#manifest_version"><code>manifest_version</code></a> 2 or above.
 </p>