chore: refine readme

Author: Justineo

README.md

@@ -24,7 +24,7 @@ Not ready yet? Read documentation for older versions [here →](https://github.c
 ### npm & ESM
 
 ```bash
-$ npm install echarts vue-echarts
+npm install echarts vue-echarts
 ```
 
 To make `vue-echarts` work for _Vue 2_ (<2.7.0), you need to have `@vue/composition-api` installed:
@@ -501,8 +501,8 @@ The following breaking changes are introduced in `vue-echarts@6`:
 ## Local development
 
 ```bash
-$ pnpm i
-$ pnpm serve
+pnpm i
+pnpm serve
 ```
 
 Open `http://localhost:8080` to see the demo.

README.zh-Hans.md

@@ -25,7 +25,7 @@
 ### npm & ESM
 
 ```bash
-$ npm install echarts vue-echarts
+npm install echarts vue-echarts
 ```
 
 要在 _Vue 2_（<2.7.0）下使用 `vue-echarts`，需要确保 `@vue/composition-api` 已经安装：
@@ -502,8 +502,8 @@ import { THEME_KEY } from 'vue-echarts'
 ## 本地开发
 
 ```bash
-$ pnpm i
-$ pnpm serve
+pnpm i
+pnpm serve
 ```
 
 打开 `http://localhost:8080` 来查看 demo。