Add test coverage status to README
diff --git a/README.md b/README.md
index 1ead596..6a690e2 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,5 @@
[](https://travis-ci.org/stoewer/go-strcase)
+[](https://coveralls.io/github/stoewer/go-strcase?branch=master)
[](https://godoc.org/github.com/stoewer/go-strcase)
---