[Bug Report] 官网Hello world页面vue引入连接失效

### Element UI version
2.15.7

### OS/Browsers version
Microsoft Edge 版本 99.0.1150.46 (正式版本) (64 位)

### Vue version
2.6.14

### Reproduction Link
https://codepen.io/ziyoung/pen/LKNBqB

### Steps to reproduce
https://element.eleme.cn/#/zh-CN/component/installation

安装部分的helloworld页面的vue引入链接是无效的,https://unpkg.com/vue/dist/vue.js
应该替换成https://cdn.jsdelivr.net/npm/vue@2.6.14/dist/vue.js

### What is Expected?
正常运行

### What is actually happening?
崩溃