Update README.MD

Author: ohmrefresh

README.md

@@ -1,3 +1,5 @@
-[![CircleCI](https://circleci.com/gh/ohmrefresh/grafana-api.svg?style=svg)](https://circleci.com/gh/ohmrefresh/grafana-api)
+[Build status] [![CircleCI](https://circleci.com/gh/ohmrefresh/grafana-api.svg?style=svg)](https://circleci.com/gh/ohmrefresh/grafana-api)
+
+[code coverage] [![codecov](https://codecov.io/gh/ohmrefresh/grafana-api/branch/master/graph/badge.svg)](https://codecov.io/gh/ohmrefresh/grafana-api)
 
 Refer to https://github.com/appnexus/grafana-api-java-client