Add godoc badge

Author: DerAndereAndi

README.md

@@ -1,6 +1,7 @@
 # eebus-go
 
 [![Build Status](https://github.com/enbility/eebus-go/actions/workflows/default.yml/badge.svg?branch=dev)](https://github.com/enbility/eebus-go/actions/workflows/default.yml/badge.svg?branch=dev)
+[![GoDoc](https://img.shields.io/badge/godoc-reference-5272B4)](https://godoc.org/github.com/enbility/eebus-go)
 [![Coverage Status](https://coveralls.io/repos/github/enbility/eebus-go/badge.svg?branch=dev)](https://coveralls.io/github/enbility/eebus-go?branch=dev)
 [![Go report](https://goreportcard.com/badge/github.com/enbility/eebus-go)](https://goreportcard.com/report/github.com/enbility/eebus-go)