docs: add mit license badge

Author: dev-redo

Readme.md

@@ -4,6 +4,8 @@
 ![Chrome Web Store Users](https://img.shields.io/chrome-web-store/users/pjffalefhahlellpckbbiehmbljjhihl?label=users%40chrome)
 ![Chrome Web Store Rating Count](https://img.shields.io/chrome-web-store/rating-count/pjffalefhahlellpckbbiehmbljjhihl)
 ![Chrome Web Store Ratings](https://img.shields.io/chrome-web-store/rating/pjffalefhahlellpckbbiehmbljjhihl)
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
+
 
 [![Chrome Web Store](https://storage.googleapis.com/chrome-gcs-uploader.appspot.com/image/WlD8wC6g8khYWPJUsQceQkhXSlv1/UV4C4ybeBTsZt43U4xis.png)](https://chrome.google.com/webstore/detail/%ED%94%84%EB%A1%9C%EC%86%94%EB%B8%8Cpro-solve/pjffalefhahlellpckbbiehmbljjhihl/related?hl=ko)