doc:update

Author: Petterpx

README.md

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+![image-20210810161316095](https://tva1.sinaimg.cn/large/008i3skNly1gtbrg85hlhj61040k80ui02.jpg)
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 [![](https://jitpack.io/v/Petterpx/FloatingX.svg)](https://jitpack.io/#Petterpx/FloatingX) [![Scan with Detekt](https://github.com/Petterpx/FloatingX/actions/workflows/detekt-analysis.yml/badge.svg)](https://github.com/Petterpx/FloatingX/actions/workflows/detekt-analysis.yml) [![ktlint](https://img.shields.io/badge/code%20style-%E2%9D%A4-FF4081.svg)](https://ktlint.github.io/) 
 
 **FloatingX** 一个灵活且强大的 `免权限` 悬浮窗解决方案。