Remove .html extension from links

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

 <h1>Declare Permissions</h1>
 
 <p>
 To use most chrome.* APIs,
 your extension or app must declare its intent in the
 "permissions" field of the
-<a href="manifest.html">manifest</a>.
+<a href="manifest">manifest</a>.
 Each permission can be either one of a list of known strings
 (such as "geolocation")
-or a <a href="match_patterns.html">match pattern</a>
+or a <a href="match_patterns">match pattern</a>
 that gives access to one or more hosts.
 Permissions help to limit damage
 if your extension or app is compromised by malware.
 Some permissions are also displayed to users before installation,
 as detailed in
-<a href="permission_warnings.html">Permission Warnings</a>.
+<a href="permission_warnings">Permission Warnings</a>.
 </p>
 
 <p>
 If an API requires you to declare a permission in the manifest,
 then its documentation tells you how to do so.
 For example,
-the <a href="storage.html">Storage</a> page
+the <a href="storage">Storage</a> page
 shows you how to
 declare the "storage" permission.
 </p>
 
 <p id="manifest">
 Here's an example of the permissions part of a manifest file:
 </p>
 
 <pre data-filename="manifest.json">
 {{^is_apps}}
@@ skipping 28 matching lines @@
   <tr id="{{p.anchor}}">
     <td>
       <code>"{{p.name}}"</code>
     </td>
     <td>
       {{+p.description platform:platform name:p.name/}}
     </td>
   </tr>
   {{/permissions}}
 </table>