Add messaging app issue tracker to website

Author: matchboxbananasynergy

static/contact.html

@@ -221,6 +221,7 @@ <h3><a href="#standalone-apps">Standalone apps</a></h3>
                         <li><a href="https://github.com/GrapheneOS/PdfViewer/issues">PDF Viewer issue tracker</a></li>
                         <li><a href="https://github.com/GrapheneOS/Vanadium/issues">Vanadium (Chromium variant) issue tracker</a></li>
                         <li><a href="https://github.com/GrapheneOS/Camera/issues">GrapheneOS Camera app issue tracker</a></li>
+                        <li><a href="https://github.com/GrapheneOS/Messaging/issues">Messaging app issue tracker</a></li>
                     </ul>
                 </section>