Update README.md

Author: lampn9397

README.md

@@ -65,6 +65,7 @@ Reminders.getReminders();
 Reminders.addReminder({
   title: 'Wake-up reminder',
   note: 'Wake-up and have breakfast!',
+  timestamp: Date.now() * 60000 * 5, // next five minutes from current time (milliseconds)
 });
 ```