chore(contibuting): add lerna install before bootstrap

CONTRIBUTING-en-US.md

@@ -15,6 +15,10 @@ To open a Pull Request, please follow the steps below:
 ```bash
 git clone https://github.com/<your-username>/semi-design.git
 cd semi-design
+```
+Before installing the enviroment,make sure that there is a dependency of `lerna` locally, if not, should run:
+```bash
+npm install --global lerna
 ```
  - Checkout to `beta` branch, install the dependencies
 ```bash

CONTRIBUTING.md

@@ -18,6 +18,10 @@ Semi Design 团队会认真对待每一个 Pull Request。我们会 review 并
 ```bash
 git clone https://github.com/<your-username>/semi-design.git
 cd semi-design
+```
+安装环境前确保本地有`lerna`的依赖，如果没有则运行：
+```bash
+npm install --global lerna
 ```
  - 切换到 `beta` 分支，完成项目依赖安装
 ```bash