added difficultyDropdown script to options.html

Author: kiing-dom

options/options.html

@@ -65,6 +65,7 @@ <h2>FAQ / About</h2>
         </main>
     </div>
     <script src="tagDropdown.js"></script>
+    <script src="difficultyDropdown.js"></script>
     <script src="options.js"></script>
 </body>
 </html>