CONTRIBUTING: fix old rst contents, and add info about CI

CONTRIBUTING.md

@@ -6,18 +6,20 @@
 
   If you find errors in documents or want to improve, this is the easiest way to help.
   You can put your document in any format in the issue comments, then a core developer
-  will format it into reStructureText syntax and commit it to the repo.
+  will format it into Markdown syntax and commit it to the repo.
 
 * Send a pull request
 
   This way is for those who are familiar with
   [Git workflow](https://guides.github.com/introduction/flow/) and
-  [reStructureText](http://www.sphinx-doc.org/en/stable/rest.html).
+  [Markdown](http://daringfireball.net).
   A PR needs to be reviewed by at least one person before merging.
 
 ## Document format
 
-Please follow <https://github.com/sparanoid/chinese-copywriting-guidelines/blob/master/README.en-US.md>
+Please follow <https://github.com/sparanoid/chinese-copywriting-guidelines/blob/master/README.en-US.md>.
+
+Also, currently we're using Markdownlint and Autocorrect to ensure the quality of the documents. [CI would automatically run check on the PRs](.github/workflows/build.yml), and **failed PRs would not be merged**.
 
 ## Environment setup
 
@@ -70,12 +72,12 @@ For those who improved the documents, the GitHub username will be mentioned in t
 * 提交 issue
 
   如果你发现文档中有错误，你可以在 issue 中提出。你也可以在 issue 中提交改进后的文档。
-  Issue 中提交的文档可以用任何格式撰写，后面我们会把文档格式化成标准的 reStructureText 格式。
+  Issue 中提交的文档可以用任何格式撰写，后面我们会把文档格式化成标准的 Markdown 格式。
 
 * 提交 pull request
 
   如果你熟悉 [Git 的协作流程](https://guides.github.com/introduction/flow/)，
-  也熟悉 [reStructureText 格式](http://www.sphinx-doc.org/en/stable/rest.html)，
+  也熟悉 [Markdown 格式](http://daringfireball.net)，
   请 pull request。
   注意 PR 在合并前至少需要一个人进行 review。
 
@@ -85,6 +87,10 @@ For those who improved the documents, the GitHub username will be mentioned in t
 
   请参考 <https://github.com/sparanoid/chinese-copywriting-guidelines>。
 
+* CI 检查
+
+  目前我们配置了 Markdownlint 和 Autocorrect 进行基本的格式检查，[CI 会对 pull request 进行检查](.github/workflows/build.yml)，**未通过检查的 pull request 不会被合并**。
+
 ## 环境配置
 
 1. 创建虚拟环境
@@ -125,4 +131,4 @@ For those who improved the documents, the GitHub username will be mentioned in t
 
 ## 署名
 
-参与任何形式的贡献，相关的 GitHub 用户名会在[文档](https://mirrors.ustc.edu.cn/help/contributor.html)中提及。
+参与任何形式的贡献，相关的 GitHub 用户名会在[文档](https://mirrors.ustc.edu.cn/help/contributor.html)中自动生成。