📝 replace coverall badge with codecov's one

Author: haya14busa

README.mkd

@@ -1,7 +1,7 @@
 # Vim Script Parser written in Go
 
 [![Build Status](https://travis-ci.org/haya14busa/go-vimlparser.svg?branch=master)](https://travis-ci.org/haya14busa/go-vimlparser)
-[![Coverage Status](https://coveralls.io/repos/github/haya14busa/go-vimlparser/badge.svg?branch=master)](https://coveralls.io/github/haya14busa/go-vimlparser?branch=master)
+[![codecov](https://codecov.io/gh/haya14busa/go-vimlparser/branch/master/graph/badge.svg)](https://codecov.io/gh/haya14busa/go-vimlparser)
 [![Sourcegraph](https://sourcegraph.com/github.com/haya14busa/go-vimlparser/-/badge.svg)](https://sourcegraph.com/github.com/haya14busa/go-vimlparser?badge)
 [![GoDoc](https://godoc.org/github.com/haya14busa/go-vimlparser?status.svg)](https://godoc.org/github.com/haya14busa/go-vimlparser)