Code comment and document refinement

[chunericli]

Issue Description

注释编写语言集中，中英文混合看的别扭，sentinel-core中的eagleeye没任何注释，理解费劲
Type: bug report or feature request
feature request

Describe what happened (or what feature you want)

每个类加点注释说明

Describe what you expected to happen

每个单独的java类注释规范统一下，最好是全英文或者全中文，很多带有感叹号的能处理下最好了，看着别扭

How to reproduce it (as minimally and precisely as possible)

1. WarmUpController的coolDownTokens方法
2. ***Exception都存在感叹号
3. eagleeye中实现都没注释

Tell us your environment

JDK8+Windows

Anything else we need to know?

1.文档和Roadmap中的描述如果能更详细点，更有利于帮助参与建设

[sczyh30]

Hi, thanks for your suggestion. We'll refine the code comments continuously.

For roadmap, this is only a blueprint. Some of the details should be well discussed. You are welcomed to provide thoughts and advice to make our community better :)