add gitpod Ready to Code badge in the Readme.

Author: nisarhassan12

README.md

@@ -18,6 +18,7 @@
   <a href="https://www.npmjs.com/package/docsify"><img alt="npm" src="https://img.shields.io/npm/v/docsify.svg?style=flat-square"></a>
   <a href="https://github.com/QingWei-Li/donate"><img alt="donate" src="https://img.shields.io/badge/%24-donate-ff69b4.svg?style=flat-square"></a>
   <a href="https://gitter.im/docsifyjs/Lobby?utm_source=share-link&utm_medium=link&utm_campaign=share-link"><img alt="gitter" src="https://img.shields.io/gitter/room/docsifyjs/docsify.svg?style=flat-square"></a>
+  <a href="https://gitpod.io/#https://github.com/docsifyjs/docsify"><img src="https://img.shields.io/badge/Gitpod-ready--to--code-blue?logo=gitpod" alt="Gitpod Ready-to-Code"></a>
 </p>
 
 <p align="center">Gold Sponsor via <a href="https://opencollective.com/docsify">Open Collective</a></p>