docs: add free CDN tips (#10068)

docs/markdown/quickstart.en-US.md

@@ -42,12 +42,21 @@ The easiest way to use Vant is to include a CDN link in the html file, after whi
 </script>
 ```
 
+#### Free CDN
+
 You can use Vant through these free CDN services:
 
 - [jsdelivr](https://www.jsdelivr.com/package/npm/vant)
 - [cdnjs](https://cdnjs.com/libraries/vant)
 - [unpkg](https://unpkg.com/)
 
+Note: Free CDN is generally used for making prototypes or personal projects. It is not recommended to use free CDN in production environment.
+
+For enterprise developers, we recommend:
+
+- install with npm, use build tools to bundle it
+- download the scripts, host it on your own server
+
 ### CLI
 
 We recommend to use [Vue Cli](https://cli.vuejs.org/) to create a new project.

docs/markdown/quickstart.zh-CN.md

@@ -49,12 +49,21 @@ npm i vant@next -S
 </script>
 ```
 
+#### 免费 CDN
+
 你可以通过以下免费 CDN 服务来使用 Vant:
 
 - [jsdelivr](https://www.jsdelivr.com/package/npm/vant)
 - [cdnjs](https://cdnjs.com/libraries/vant)
 - [unpkg](https://unpkg.com/)
 
+注意：免费 CDN 一般用于制作原型或个人小型项目，不推荐在企业生产环境中使用免费 CDN。
+
+对于企业开发者，建议使用以下方式：
+
+- 通过 npm 引入，并通过构建工具进行打包
+- 下载对应文件，并托管在你自己的服务器或 CDN 上
+
 ### 通过脚手架安装
 
 在新项目中使用 Vant 时，推荐使用 Vue 官方提供的脚手架 [Vue Cli](https://cli.vuejs.org/zh/) 创建项目并安装 Vant。