docs: add dumi badge

Author: xrkffgg

README.md

@@ -2,7 +2,7 @@
 
 React Tooltip
 
-[![NPM version][npm-image]][npm-url] [![build status][github-actions-image]][github-actions-url]  [![Test coverage][coveralls-image]][coveralls-url] [![gemnasium deps][gemnasium-image]][gemnasium-url] [![node version][node-image]][node-url] [![npm download][download-image]][download-url]
+[![NPM version][npm-image]][npm-url] [![dumi](https://img.shields.io/badge/docs%20by-dumi-blue?style=flat-square)](https://github.com/umijs/dumi) [![build status][github-actions-image]][github-actions-url]  [![Test coverage][coveralls-image]][coveralls-url] [![gemnasium deps][gemnasium-image]][gemnasium-url] [![node version][node-image]][node-url] [![npm download][download-image]][download-url]
 
 [npm-image]: https://img.shields.io/npm/v/rc-tooltip.svg?style=flat-square
 [npm-url]: https://npmjs.org/package/rc-tooltip