clarify no-build setup usage

close #1677

Author: yyx990803

src/guide/quick-start.md

@@ -74,7 +74,9 @@ To get started with Vue without a build step, simply copy the following code int
 <div id="app">{{ message }}</div>
 
 <script>
-  Vue.createApp({
+  const { createApp } = Vue
+
+  createApp({
     data() {
       return {
         message: 'Hello Vue!'
@@ -84,7 +86,11 @@ To get started with Vue without a build step, simply copy the following code int
 </script>
 ```
 
-The above example uses the global build of Vue where all APIs are exposed under the global `Vue` variable.
+The above example uses the global build of Vue where all APIs are exposed under the global `Vue` variable. For example, to also use the `ref` API, you can do:
+
+```js
+const { createApp, ref } = Vue
+```
 
 While the global build works, we will be primarily using [ES modules](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules) syntax throughout the rest of the documentation for consistency. In order to use Vue over native ES modules, use the following HTML instead:
 
@@ -112,11 +118,15 @@ While the global build works, we will be primarily using [ES modules](https://de
 </script>
 ```
 
-Notice how we can import directly from `'vue'` in our code - this is made possible by the `<script type="importmap">` block, leveraging a native browser feature called [Import Maps](https://caniuse.com/import-maps). Import maps are currently only available in Chromium-based browsers, so we recommend using Chrome or Edge during the learning process. If your preferred browser does not support import maps yet, you can polyfill it with [es-module-shims](https://github.com/guybedford/es-module-shims).
+Notice how we can import directly from `'vue'` in our code - this is made possible by the `<script type="importmap">` block, leveraging a native browser feature called [Import Maps](https://caniuse.com/import-maps).
 
 You can add entries for other dependencies to the import map - just make sure they point to the ES modules version of the library you intend to use.
 
-:::tip Not for production
+:::tip Import Maps Browser Support
+Import maps are currently only available in Chromium-based browsers, so we recommend using Chrome or Edge during the learning process. If your preferred browser does not support import maps yet, you can polyfill it with [es-module-shims](https://github.com/guybedford/es-module-shims).
+:::
+
+:::warning Not for production
 The import-maps-based setup is meant for learning only - if you intend to use Vue without build tools in production, make sure to check out the [Production Deployment Guide](/guide/best-practices/production-deployment.html#without-build-tools).
 :::