Update about.html

Added @menghif to special thanks section

Author: piechowiakmichal

about.html

@@ -107,6 +107,8 @@ <h2>Contributors</h2>
             href="https://github.com/many-passwords/many-passwords.github.io/pull/8">pull/8;</a></li>
         <li><a href="https://github.com/NgoQuocBao1010">@NgoQuocBao1010</a> - <a
             href="https://github.com/many-passwords/many-passwords.github.io/issues/20">added buttons for downloads passwords to CSV and JSON file and displaying the number of collected passwords on the home page;</a></li>
+        <li><a href="https://github.com/menghif">@menghif</a> - <a
+            href="https://github.com/many-passwords/many-passwords.github.io/pull/28">website optimization for the user and the search engine;</a></li>
         <li><a href="https://github.com/many-passwords/many-passwords/graphs/contributors">@all contributors</a> - I
           cannot list all of you, thank you all for your contribution!</li>
       </ul>