docs: fix quickstart

docs/markdown/quickstart.en-US.md

@@ -121,7 +121,7 @@ The easiest way to use Vant is to include a CDN link in the html file, after whi
   vant.Toast('Message');
 
   // Register Lazyload directive
-  Vue.use(vant.Lazyload);
+  // app.use(vant.Lazyload);
 </script>
 ```
 

docs/markdown/quickstart.zh-CN.md

@@ -139,7 +139,7 @@ app.use(Vant);
 
   // 通过 CDN 引入时不会自动注册 Lazyload 组件
   // 可以通过下面的方式手动注册
-  Vue.use(vant.Lazyload);
+  // app.use(vant.Lazyload);
 </script>
 ```