fix: demo code-block sample

src/pages/demo/index.html

@@ -75,7 +75,7 @@
     <main>
       <a href="/demo/about">{{ count }}</a>
       <div>
-        <my-hello-world name="{{name }}"></my-hello-world>
+        <my-hello-world data-name="{{name }}"></my-hello-world>
       </div>
       <p>some text: {{greeting}}</p>
       {{greeting}} hey<br />