Update and add index

html/certificates.html

@@ -1955,6 +1955,10 @@ Relationship Management</a></td>
 </tr>
 </tbody>
 </table>
+<h2 id="contributors">Contributors</h2>
+<p><a href="https://github.com/panxproject/awesome-certificates/graphs/contributors">
+<img src="https://contrib.rocks/image?repo=panxproject/awesome-certificates" />
+</a></p>
 <h2 id="other-awesome-lists">Other Awesome Lists</h2>
 <ul>
 <li><a href="https://github.com/ossu/computer-science">Open Source