fix: demo sample code missing code-block

src/pages/demo/index.html

@@ -77,6 +77,7 @@
       <div>
         <my-hello-world data-name="{{name }}"></my-hello-world>
       </div>
+      <code-block language="js">const name = "Nitro"</code-block>
       <p>some text: {{greeting}}</p>
       {{greeting}} hey<br />
       <clickable-text></clickable-text>