[DOC] detail document for all plugin

This issue is to improve our home website plugin document.
With our new document, everyone can easily know and use our native plugin:
New Plugin Document Template:
1. Overview
1.1 Plugin Name
1.2 Appropriate Scenario
1.3 Plugin functionality
1.4 Plugin code
1.5 Added Since Which shenyu version
2. How to use plugin
2.1 Plugin-use procedure chart
2.2 Import pom
2.3 Enable plugin
2.4 Config plugin
key config class
describe every page config item so that everyone knows config detail, can contain examples and picture
2.5 Examples
2.5.1 examples1, text and snapshot, detail describe every page config item, request, result
2.5.2 examples2, text and snapshot, detail describe every page config item, request, result
3. How to disable plugin

1. 概述：
1.1 插件名称
1.2 适用场景
1.3 插件功能
1.4 插件代码
1.5 添加自哪个shenyu版本
2. 如何使用插件
2.1 插件使用流程图
2.2 导入pom
2.3 启用插件
2.4 配置插件
2.5 示例
2.5.1 示例1，文本和快照，详细描述每个页面配置项，请求，结果
2.5.2 示例2，文本和快照，详细描述每个页面配置项，请求，结果
3. 如何禁用插件

We welcome users to provide best practice to give us more ideas or help us improve specific native plugin.

- [ ] Authentication-Sign plugin blocked for bug
- [ ] Authentication-Jwt Plugin
- [ ] Authentication-Oauth2 Plugin
- [ ] Authentication-Waf Plugin
- [ ] FaultTolerance-Ratelimiter Plugin
- [ ] FaultTolerance-Hystrix Plugin @[erdengk](https://github.com/erdengk)
- [ ] FaultTolerance-Sentinel Plugin @moremind
- [ ] FaultTolerance-REsilience4j Plugin
- [ ] HttpProcess-ParamMapping Plugin
- [x] HttpProcess-ContextPath Plugin @AhahaGe finished
- [ ] HttpProcess-Rewrite Plugin
- [ ] HttpProcess-Redirect Plugin
- [ ] HttpProcess-Request Plugin
- [ ] HttpProcess-ModifyResponse Plugin
- [ ] Proxy-Mqtt Plugin @[selectbook](https://github.com/selectbook)
- [ ] Proxy-SpringCloud Plugin
- [ ] Proxy-Websocket Plugin
- [x] Proxy-Divide Plugin @AhahaGe
- [ ] Proxy-Grpc Plugin
- [ ] Proxy-Motan Plugin
- [ ] Proxy-Tars Plugin
- [ ] Proxy-Sofa Plugin
- [ ] Proxy-Dubbo Plugin
- [ ] Common-GeneralContext Plugin
- [ ] Logging-Loggin Plugin @moremind
- [ ] Monitor-Monitor Plugin