Adding coverage banner in README

README.md

@@ -1,8 +1,13 @@
 # MLJFlow
 
-| Branch | Build |
-| :---: | :---: |
-| dev | [![CI](https://github.com/pebeto/MLJFlow.jl/actions/workflows/CI.yml/badge.svg?branch=dev)](https://github.com/pebeto/MLJFlow.jl/actions/workflows/CI.yml) |
+| Branch | Build | Coverage |
+| :---: | :---: | :---: |
+| dev | [![Continuous Integration (CPU)][ci-dev-img]][ci-dev] | [![Code Coverage][codecov-dev-img]][codecov-dev] |
+
+[ci-dev]: https://github.com/pebeto/MLJFlow.jl/actions/workflows/CI.yml
+[ci-dev-img]: https://github.com/pebeto/MLJFlow.jl/actions/workflows/CI.yml/badge.svg?branch=dev "Continuous Integration (CPU)"
+[codecov-dev]: https://codecov.io/github/JuliaAI/MLJFlow.jl?branch=dev
+[codecov-dev-img]: https://codecov.io/gh/JuliaAI/MLJFlow.jl/branch/dev/graphs/badge.svg?branch=dev "Code Coverage"
 
 [MLJ](https://github.com/alan-turing-institute/MLJ.jl) is a Julia framework for
 combining and tuning machine learning models. MLJFlow is a package that extends