Remove .html extension from links

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

 <h1 id="requirements">Manifest - Requirements</h1>
 
 <p>
 Technologies required by the app or extension.
 Hosting sites such as the Chrome Web Store may use this list
 to dissuade users from installing apps or extensions
 that will not work on their computer.
 Supported requirements currently include "3D" and "plugins";
 additional requirements checks may be added in the future.
 </p>
@@ skipping 15 matching lines @@
     "features": ["webgl"]
   }
 }
 </pre>
 
 <p>
 The "plugins" requirement indicates
 if an app or extension requires NPAPI to run.
 This requirement is enabled by default
 when the manifest includes the
-<a href="http://developer.chrome.com/extensions/npapi.html">"plugins" field</a>.
+<a href="http://developer.chrome.com/extensions/npapi">"plugins" field</a>.
 For apps and extensions that still work when plugins aren't available,
 you can disable this requirement
 by setting NPAPI to false.
 You can also enable this requirement manually,
 by setting NPAPI to true,
 as shown in this example:
 </p>
 
 <pre data-filename="manifest.json">
 "requirements": {
   "plugins": {
     "npapi": true
   }
 }
 </pre>