Add ci badge (#25)

README.md

@@ -1,7 +1,9 @@
 # axios-logger
+
 [![npm](https://img.shields.io/npm/v/axios-logger.svg)](https://www.npmjs.com/package/axios-logger)
 [![npm](https://img.shields.io/npm/dm/axios-logger.svg)](https://www.npmjs.com/package/axios-logger)
 [![GitHub license](https://img.shields.io/github/license/hg-pyun/axios-logger.svg)](https://github.com/hg-pyun/axios-logger/blob/master/LICENSE)
+[![CircleCI](https://circleci.com/gh/hg-pyun/axios-logger/tree/master.svg?style=svg)](https://circleci.com/gh/hg-pyun/axios-logger/tree/master)
 
 > Beautify Axios Logging Messages.
 
@@ -76,7 +78,7 @@ instance.interceptors.response.use(AxiosLogger.responseLogger, AxiosLogger.error
 Also if you want to use your own interceptor, you can compose(mixin) with `errorLogger`.
 
 ```javascript
-instance.interceptors.response.use(AxiosLogger.responseLogger, (err) =>{
+instance.interceptors.response.use(AxiosLogger.responseLogger, (err) => {
     // write down your error intercept.
     return AxiosLogger.errorLogger(err);
 });