Add dark mode module again (#759)

src/_includes/layouts/base.njk

@@ -53,6 +53,7 @@
       </div>
       <p><small>Except as otherwise noted, any code samples from the V8 project are licensed under <a href="https://chromium.googlesource.com/v8/v8.git/+/main/LICENSE">V8’s BSD-style license</a>. Other content on this page is licensed under <a href="https://creativecommons.org/licenses/by/3.0/">the Creative Commons Attribution 3.0 License</a>. For details, see <a href="/terms#site-policies">our site policies</a>.</small></p>
     </footer>
+    <script type="module" src="/_js/dark-mode-toggle.mjs"></script>
     <script src="/_js/main.js"></script>
   </body>
 </html>