Update README.md

Author: b-yogesh

chartlets.js/README.md

@@ -1,6 +1,7 @@
 # Chartlets 
 
 [![CI](https://github.com/bcdev/chartlets/actions/workflows/frontend-ci.yml/badge.svg)](https://github.com/bcdev/chartlets/actions/workflows/frontend-ci.yml)
+[![codecov](https://codecov.io/gh/bcdev/chartlets/graph/badge.svg?token=zJBPMFvnpg)](https://codecov.io/gh/bcdev/chartlets/chartlets.js/packages/lib)
 [![npm](https://badge.fury.io/js/chartlets.svg)](https://npmjs.org/package/chartlets)
 ![](https://img.shields.io/badge/Linting-TypeScript%20%26%20Prettier-blue?logo=typescript&logoColor=white)