Add badges for coverage to README (#44)

* add badges for coverage to README

* test if CI runs

* remove newline again

README.md

@@ -1,6 +1,8 @@
 # MeshIntegrals.jl
 
 [![Build Status](https://github.com/mikeingold/MeshIntegrals.jl/actions/workflows/CI.yml/badge.svg?branch=main)](https://github.com/mikeingold/MeshIntegrals.jl/actions/workflows/CI.yml?query=branch%3Amain)
+[![codecov](https://codecov.io/gh/mikeingold/MeshIntegrals.jl/graph/badge.svg)](https://codecov.io/gh/mikeingold/MeshIntegrals.jl)
+[![Coveralls](https://coveralls.io/repos/github/mikeingold/MeshIntegrals.jl/badge.svg?branch=main)](https://coveralls.io/github/mikeingold/MeshIntegrals.jl?branch=main)
 [![Aqua QA](https://raw.githubusercontent.com/JuliaTesting/Aqua.jl/master/badge.svg)](https://github.com/JuliaTesting/Aqua.jl)
 [![License: MIT](https://img.shields.io/badge/License-MIT-success.svg)](https://opensource.org/licenses/MIT)