doc: add Contributing Guide

CONTRIBUTING.en-US.md

@@ -0,0 +1,37 @@
+# Lancet Contributing Guide
+
+Hi! Thank you for choosing Lancet.
+
+Lancet is a powerful, efficient, and reusable util function library of go. It makes Go dev easier by taking the hassle out of working with concurrency, net, math, slice, string, etc.
+
+We are excited that you are interested in contributing to lancet. Before submitting your contribution though, please make sure to take a moment and read through the following guidelines.
+
+## Issue Guidelines
+
+- Issues are exclusively for bug reports, feature requests and design-related topics. Other questions may be closed directly.
+
+- Before submitting an issue, please check if similar problems have already been issued.
+
+- Please specify which version of Lancet and Go you are using, and provide OS information. [Go Playground](https://go.dev/play/) is recommended to build a live demo so that your issue can be reproduced clearly.
+
+## Pull Request Guidelines
+
+- Fork this repository to your own account. Do not create branches here.
+
+- Commit info should be formatted as `type(scope): info about commit`. eg. `fix(package): [scrollbar] fix xxx bug`.
+
+  1. type: type must be one of [chore, docs, feat, fix, refactor, release, test].
+
+  2. scope: scope must be one of [package, file, internal].
+
+  3. header: header must not be longer than 72 characters.
+
+- Rebase before creating a PR to keep commit history clear.
+
+- Before submitting a PR, please execute the unit test command: `go test -v ./...` to ensure that all unit test tasks should pass.
+
+- Make sure PRs are created to `v2` branch instead of `master` branch.
+
+- If your PR fixes a bug, please provide a description about the related bug.
+
+- Merging a PR takes two maintainers: one approves the changes after reviewing, and then the other reviews and merges.

CONTRIBUTING.zh-CN.md

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+# Lancet 贡献指南
+
+Hi! 首先感谢你使用 Lancet。
+
+lancet（柳叶刀）是一个功能强大、全面、高效、可复用的go语言工具函数库。它消除了处理并发、网络、数学、切片、字符串等的麻烦，使 Go 开发变得更容易。
+
+Lancet 的成长离不开大家的支持，如果你愿意为 Lancet 贡献代码或提供建议，请阅读以下内容。
+
+## Issue 规范
+
+- issue 仅用于提交 Bug 或 Feature 以及设计相关的内容，其它内容可能会被直接关闭。
+
+- 在提交 issue 之前，请搜索相关内容是否已被提出。
+
+- 请说明 Lancet 和 Go 的版本号，并提供操作系统信息。推荐使用 [Go Playground](https://go.dev/play/) 生成在线 demo，这能够更直观地重现问题。
+
+## Pull Request 规范
+
+- 请先 fork 一份到自己的项目下，不要直接在仓库下建分支。
+
+- commit 信息要以 `type(scope): 描述信息` 的形式填写，例如 `fix(package): [scrollbar] fix xxx bug`。
+
+  1. type: 必须是 chore, docs, feat, fix, refactor, release, test 其中的一个。
+
+  2. scope: 必须是 package, file, internal 其中的一个。
+
+  3. header: 描述信息不要超过 72 个字符。
+
+- 提交 PR 前请 rebase，确保 commit 记录的整洁。
+
+- 提交 PR 前请执行单元测试命令：go test -v ./...，确保所有单元测试任务通过。
+
+- 确保 PR 是提交到 `v2` 分支，而不是 `main` 分支。
+
+- 如果是修复 bug，请在 PR 中给出描述信息。
+
+- 合并代码需要两名维护人员参与：一人进行 review 后 approve，另一人再次 review，通过后即可合并。

README.md

@@ -1877,10 +1877,4 @@ import "github.com/duke-git/lancet/v2/xerror"
 
 ## How to Contribute
 
-I really appreciate any code commits which make lancet lib powerful. Please follow the rules below to create your pull request.
-
-1. Fork the repository.
-2. Create your feature branch.
-3. Commit your changes.
-4. Push to the branch
-5. Create new pull request.
+#### [Contributing Guide](./CONTRIBUTING.en-US.md)

README_zh-CN.md

@@ -1884,10 +1884,5 @@ import "github.com/duke-git/lancet/v2/xerror"
 
 ## 如何贡献代码
 
-非常感激任何的代码提交以使 lancet 的功能越来越强大。创建 pull request 时请遵守以下规则。
+#### [贡献代码指南](./CONTRIBUTING.zh-CN.md)
 
-1. Fork lancet 仓库。
-2. 创建自己的特性分支。
-3. 提交变更。
-4. Push 分支。
-5. 创建新的 pull request。