docs: add pkg.go.dev badge

Author: christophwitzko

README.md

@@ -3,6 +3,7 @@
 [![Build Status](https://travis-ci.org/go-semantic-release/semantic-release.svg?branch=master)](https://travis-ci.org/go-semantic-release/semantic-release)
 [![pipeline status](https://gitlab.com/go-semantic-release/semantic-release/badges/master/pipeline.svg)](https://gitlab.com/go-semantic-release/semantic-release/pipelines)
 [![Go Report Card](https://goreportcard.com/badge/github.com/go-semantic-release/semantic-release)](https://goreportcard.com/report/github.com/go-semantic-release/semantic-release)
+[![PkgGoDev](https://pkg.go.dev/badge/github.com/go-semantic-release/semantic-release)](https://pkg.go.dev/github.com/go-semantic-release/semantic-release)
 
 > fully automated package/module/image publishing