Fix some typos, broken links and other issues in extension docs

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

 <h1>Offline First</h1>
 
 
 <p>
 Because internet connections can be flakey or non-existent,
 you need to consider <em>offline first</em>:
 write your app as if it has no internet connection.
 Once your app works offline,
 add whatever network functionality you need
 for your app to do more when it’s online.
@@ skipping 168 matching lines @@
        Easy to sync remotely (but you don't have to).
        Not good for larger amounts of data,
        due to quotas.
        </td>
 </tr>
 <tr>
   <td> IndexedDB API </td>
   <td> Structured data </td>
   <td> Enables fast searches on data.
        Use with the
-       <a href="manifest.html#permissions">unlimitedStorage permission</a>. </td>
+       <a href="declare_permissions.html">unlimitedStorage permission</a>. </td>
 </tr>
 <tr>
   <td> Filesystem API </td>
   <td> Anything else </td>
   <td> Provides a sandboxed area where you can store files.
        Use with the
-       <a href="manifest.html#permissions">unlimitedStorage permission</a>. </td>
+       <a href="declare_permissions.html">unlimitedStorage permission</a>. </td>
 </tr>
 </table>
 
 <p class="note">
 <b>Note:</b>
 Packaged apps cannot use Web SQL Database or localStorage.
 The WebSQL specification has been deprecated for awhile now,
 and localStorage handles data synchronously
 (which means it can be slow).
 The Storage API handles data asynchronously.
@@ skipping 87 matching lines @@
     switching often between online and offline.
   </li>
 </ul>
 
 <p>
 Also make sure that the app saves <b>no sensitive user data</b>
 (such as passwords) on the user's machine.
 </p>
 
 <p class="backtotop"><a href="#top">Back to top</a></p>