adds html rich preview

src/main/resources/META-INF/resources/app.js

@@ -165,6 +165,13 @@ function hideSnackbar() {
 }
 
 document.addEventListener("DOMContentLoaded", async () => {
+
+    document.querySelector('meta[property="og:url"]').setAttribute("content", url());
+    document.querySelector('meta[property="twitter:url"]').setAttribute("content", url());
+    document.querySelector('meta[property="og:image"]').setAttribute("content", url() + '/rich.png');
+    document.querySelector('meta[name="twitter:image"]').setAttribute("content", url() + '/rich.png');
+    document.querySelector('meta[property="twitter:domain"]').setAttribute("content", window.location.hostname);
+
     if (localStorage.getItem('last-name') && localStorage.getItem('last-room')) {
         document.getElementById('name').value = localStorage.getItem('last-name');
         document.getElementById('room').value = localStorage.getItem('last-room');