doc: badges

README.md

@@ -1,7 +1,7 @@
 ![npm version](https://img.shields.io/node/v/xmysql.svg)
 [![Build Status](https://travis-ci.org/o1lab/xmysql.svg?branch=master)](https://travis-ci.org/o1lab/xmysql)
 [![GitHub stars](https://img.shields.io/github/stars/o1lab/xmysql.svg?style=plastic)](https://github.com/o1lab/xmysql/stargazers)
-[![Twitter](https://img.shields.io/twitter/url/https/github.com/o1lab/xmysql.svg?style=social)](https://twitter.com/intent/tweet?text=Wow:&url=%5Bobject%20Object%5D)
+[![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/o1lab/xmysql/master/LICENSE)
 [![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/o1lab/xmysql/master/LICENSE)
 
 # xmysql: one command to generate REST APIs for **any** MySql database