docs: Update Authentik example (#9950)

* Update

* npm run format:fix

* more npm run format:fix

docs/src/css/custom.css

@@ -15,6 +15,10 @@ button {
   font-family: 'Overpass', sans-serif;
 }
 
+img {
+  border-radius: 15px;
+}
+
 /* You can override the default Infima variables here. */
 :root {
   --ifm-color-primary: #4250af;