Merge branch 'master' of https://github.com/opensource9ja/danfojs

Author: risenW

README.md

@@ -9,6 +9,7 @@
 ![Node.js CI](https://github.com/opensource9ja/danfojs/workflows/Node.js%20CI/badge.svg?branch=master)
 [![](https://data.jsdelivr.com/v1/package/npm/danfojs/badge?style=rounded)](https://www.jsdelivr.com/package/npm/danfojs)
 [![Build Status](https://travis-ci.org/opensource9ja/danfojs.svg?branch=master)](https://travis-ci.org/opensource9ja/danfojs)
+[![Coverage Status](https://coveralls.io/repos/github/opensource9ja/danfojs/badge.svg)](https://coveralls.io/github/opensource9ja/danfojs)
 ![Twitter](https://img.shields.io/twitter/url?style=social&url=https%3A%2F%2Ftwitter.com%2FDanfoJs)