add link to gocov report on drone.io

README.md

@@ -4,7 +4,7 @@ go-github is Go library for accessing the [GitHub API][].
 
 **Documentation:** <http://godoc.org/github.com/google/go-github/github>  
 **Build Status:** [![Build Status](https://travis-ci.org/google/go-github.png?branch=master)](https://travis-ci.org/google/go-github)  
-**Test Coverage:** [![Test Coverage](https://coveralls.io/repos/google/go-github/badge.png?branch=master)](https://coveralls.io/r/google/go-github?branch=master)
+**Test Coverage:** [![Test Coverage](https://coveralls.io/repos/google/go-github/badge.png?branch=master)](https://coveralls.io/r/google/go-github?branch=master) ([gocov report](https://drone.io/github.com/google/go-github/files/coverage.html))
 
 go-github requires Go version 1.1.