Use bundled CDN import for demo

Author: hanityx

demo/index.html

@@ -474,7 +474,7 @@ <h2 id="final-check">Final check</h2>
     </main>
     <script type="module">
       const moduleUrl = location.hostname.endsWith("github.io")
-        ? "https://cdn.jsdelivr.net/npm/toc-rail@0.1.3/dist/index.js"
+        ? "https://cdn.jsdelivr.net/npm/toc-rail@0.1.3/+esm"
         : "../dist/index.js?v=demo-0.1.3";
       const { mountTocRail } = await import(moduleUrl);