【docs】：Code example 'setup' is missing (#7153)

* flx

* flx【docs】:Modify the official website code example, switch TS to JS, the top of the example should be '<script setup>'

plugin/md/markdownToVue.ts

@@ -86,7 +86,7 @@ ${vueCode?.trim()}
   const scriptContent = fetchCode(vueCode, 'scriptContent');
   let jsCode = (await tsToJs(scriptContent))?.trim();
   jsCode = jsCode
-    ? `<script>
+    ? `<script setup>
 ${jsCode}
 </script>`
     : '';