[Chore] Add contributing in README.

README.md

@@ -41,12 +41,39 @@ If you use Metal, you can easily reuse these plugins. Metal provides two ways to
 ## Architecture
 [Architecture](/doc/Architecture.md)
 
+## How to Contribute
+
+Thanks for your interest in contributing! The easiest way is to just send a pull request(PR). Before send a PR, you need to understand how to build the source code and do somethings.
+
+### Building From source
+
+Building Metal requires at minimum JDK 11. Pull the latest source from the repository and use Maven install (or package) to build:
+
+```shell
+git pull origin master
+mvn clean package -pl metal-dist -am -Dmaven.test.skip=true 
+```
+
+### Before Send a pull request
+
+Please check code format and fix the `spotless` errors if any:
+
+```shell
+mvn spotless:check
+```
+
+More details in [Contributing.md](CONTRIBUTING.md).
+
 ## Code of Conduct
-[CODE_OF_CONDUCT](/CODE_OF_CONDUCT.md)
+[CODE_OF_CONDUCT](CODE_OF_CONDUCT.md)
 
+## Security
+[Security.md](SECURITY.md)
 ## Sponsor
 <img src="https://resources.jetbrains.com/storage/products/company/brand/logos/jb_beam.svg" alt="JetBrains Logo (Main) logo.">
 <strong>Thanks to JetBrains for the <a target="_blank" href="https://jb.gg/OpenSourceSupport">free license</a>.</strong><br>
 
 ## License
 [Apache 2.0 License.](LICENSE)
+
+

README_cn.md

@@ -41,9 +41,36 @@ Metal是一款数据流建模软件，通过Metal可以管理数据流处理算
 ## Architecture
 [Architecture](/doc/Architecture_cn.md)
 
+## How to Contribute
+
+感谢您对本项目贡献的兴趣! 了解如何对项目做贡献的最简单的方式是提交一次PR。在正式发起PR前，你需要了解如何构建源码以及提交前的主要事项。
+
+### 从源码构建
+
+构建Metal，需要使用JDK 11及以上版本。从仓库拉取最新代码，然后使用`maven`执行构建：
+
+```shell
+git pull origin master
+mvn clean package -pl metal-dist -am -Dmaven.test.skip=true 
+```
+
+### 提交PR前的注意项
+
+通过如下命令检查代码格式:
+
+```shell
+mvn spotless:check
+```
+
+您需要保证在发起PR前，已经修复了全部`spotless`错误。
+
+更多细节见[Contributing.md](CONTRIBUTING.md).
+
 ## Code of Conduct
-[CODE_OF_CONDUCT](/CODE_OF_CONDUCT.md)
+[CODE_OF_CONDUCT](CODE_OF_CONDUCT.md)
 
+## Security
+[Security.md](SECURITY.md)
 ## Sponsor
 <img src="https://resources.jetbrains.com/storage/products/company/brand/logos/jb_beam.svg" alt="JetBrains Logo (Main) logo.">
 <strong>Thanks to JetBrains for the <a target="_blank" href="https://jb.gg/OpenSourceSupport">free license</a>.</strong><br>