[Doc] add touch emulator guide

docs/markdown/quickstart.zh-CN.md

@@ -153,3 +153,16 @@ module.exports = {
 ```
 
 > 注意：在配置 postcss-loader 时，应避免 ignore node_modules 目录，这会导致 Vant 的样式无法被编译
+
+### 在桌面端使用
+
+Vant 组件默认只适配了移动端设备，如果你需要在桌面端使用 vant，可以引入我们提供的 [@vant/touch-emulator](https://github.com/chenjiahan/vant-touch-emulator).
+
+```bash
+npm i @vant/touch-emulator -S
+```
+
+```js
+// 引入模块后自动生效
+import '@vant/touch-emulator';
+```

docs/src/mobile.js

@@ -4,7 +4,7 @@ import VueRouter from 'vue-router';
 import { progress } from '@vant/doc';
 import App from './WapApp';
 import routes from './router';
-import '@vant/doc/helper/touch-simulator';
+import '@vant/touch-emulator';
 
 const router = new VueRouter({
   mode: 'hash',

package.json

@@ -74,6 +74,7 @@
     "@vant/doc": "^2.2.4",
     "@vant/eslint-config": "^1.1.2",
     "@vant/markdown-loader": "^2.0.0",
+    "@vant/touch-emulator": "^1.0.0",
     "@vue/babel-preset-jsx": "^1.0.0",
     "@vue/server-test-utils": "^1.0.0-beta.29",
     "@vue/test-utils": "^1.0.0-beta.29",

yarn.lock

@@ -1109,6 +1109,11 @@
     highlight.js "^9.15.6"
     markdown-it "^8.4.2"
 
+"@vant/touch-emulator@^1.0.0":
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/@vant/touch-emulator/-/touch-emulator-1.0.0.tgz#e9ea133fd874a534481c84e12089b2e9d552544b"
+  integrity sha512-XDiQ4Cp7uU1PjsNwyXBymnH6f1I0hwEGa0HN0fvGstP7oFb8QGICUNMiNV0PHmYiBdql60lk1oTGi+refLypGQ==
+
 "@vue/babel-helper-vue-jsx-merge-props@^1.0.0":
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/@vue/babel-helper-vue-jsx-merge-props/-/babel-helper-vue-jsx-merge-props-1.0.0.tgz#048fe579958da408fb7a8b2a3ec050b50a661040"