feat: add option to try project on CodeSandbox (PanJiaChen#2976)

Author: garethx

README.es.md

@@ -62,6 +62,8 @@ Vue Element Admin es una solución práctica basada en la nueva plataforma de de
 Necesita instalar [node](https://nodejs.org/) y [git](https://git-scm.com/) localmente. El proyecto es basado en [ES2015+](https://es6.ruanyifeng.com/), [vue](https://cn.vuejs.org/index.html), [vuex](https://vuex.vuejs.org/zh-cn/), [vue-router](https://router.vuejs.org/zh-cn/), [vue-cli](https://github.com/vuejs/vue-cli) , [axios](https://github.com/axios/axios) and [element-ui](https://github.com/ElemeFE/element), toda la solicitud de datos simulada se realiza a través de [Mock.js](https://github.com/nuysoft/Mock).
 Entendiendo y aprendiendo esto pudiera ayudarle con su proyecto.
 
+[![Edit on CodeSandbox](https://codesandbox.io/static/img/play-codesandbox.svg)](https://codesandbox.io/s/github/PanJiaChen/vue-element-admin/tree/CodeSandbox)
+
  <p align="center">
   <img width="900" src="https://wpimg.wallstcn.com/a5894c1b-f6af-456e-82df-1151da0839bf.png">
 </p>

README.ja.md

@@ -59,6 +59,8 @@
 
 **バグ修正や新規機能追加のissue と pull requestは大歓迎です。**
 
+[![Edit on CodeSandbox](https://codesandbox.io/static/img/play-codesandbox.svg)](https://codesandbox.io/s/github/PanJiaChen/vue-element-admin/tree/CodeSandbox)
+
  <p align="center">
   <img width="900" src="https://wpimg.wallstcn.com/a5894c1b-f6af-456e-82df-1151da0839bf.png">
 </p>

README.md

@@ -62,6 +62,8 @@ English | [简体中文](./README.zh-CN.md) | [日本語](./README.ja.md) | [Spa
 You need to install [node](https://nodejs.org/) and [git](https://git-scm.com/) locally. The project is based on [ES2015+](https://es6.ruanyifeng.com/), [vue](https://cn.vuejs.org/index.html), [vuex](https://vuex.vuejs.org/zh-cn/), [vue-router](https://router.vuejs.org/zh-cn/), [vue-cli](https://github.com/vuejs/vue-cli) , [axios](https://github.com/axios/axios) and [element-ui](https://github.com/ElemeFE/element), all request data is simulated using [Mock.js](https://github.com/nuysoft/Mock).
 Understanding and learning this knowledge in advance will greatly help the use of this project.
 
+[![Edit on CodeSandbox](https://codesandbox.io/static/img/play-codesandbox.svg)](https://codesandbox.io/s/github/PanJiaChen/vue-element-admin/tree/CodeSandbox)
+
  <p align="center">
   <img width="900" src="https://wpimg.wallstcn.com/a5894c1b-f6af-456e-82df-1151da0839bf.png">
 </p>

README.zh-CN.md

@@ -77,6 +77,8 @@
 
 **如有问题请先看上述使用文档和文章，若不能满足，欢迎 issue 和 pr**
 
+[![Edit on CodeSandbox](https://codesandbox.io/static/img/play-codesandbox.svg)](https://codesandbox.io/s/github/PanJiaChen/vue-element-admin/tree/CodeSandbox)
+
  <p align="center">
   <img width="900" src="https://wpimg.wallstcn.com/a5894c1b-f6af-456e-82df-1151da0839bf.png">
 </p>