Add a title to notification close button

Author: shepmaster

ui/frontend/Notifications.tsx

@@ -121,7 +121,7 @@ interface NotificationProps {
 const Notification: React.FC<NotificationProps> = ({ onClose, children }) => (
   <div className={styles.notification} data-test-id="notification">
     <div className={styles.notificationContent}>{children}</div>
-    <button className={styles.close} onClick={onClose}>
+    <button className={styles.close} onClick={onClose} title="dismiss notification">
       <Close />
     </button>
   </div>