added shield for go report which includes gofmt and other metrics

ReadMe.Md

@@ -3,6 +3,7 @@
 [![Dependabot](https://badgen.net/badge/Dependabot/enabled/green?icon=dependabot)](https://github.com/simonmittag/j8a/pulls?q=is%3Aopen+is%3Apr)
 [![Github Issues](https://img.shields.io/github/issues/simonmittag/j8a)](https://github.com/simonmittag/j8a/issues)
 [![Github Activity](https://img.shields.io/github/commit-activity/m/simonmittag/j8a)](https://img.shields.io/github/commit-activity/m/simonmittag/j8a)  
+[![Go Report](https://goreportcard.com/badge/github.com/simonmittag/j8a)](https://goreportcard.com/badge/github.com/simonmittag/j8a)
 [![Codeclimate Maintainability](https://api.codeclimate.com/v1/badges/326d3c304e32645811c8/maintainability)](https://codeclimate.com/github/simonmittag/jabba/maintainability)
 [![Codeclimate Test Coverage](https://api.codeclimate.com/v1/badges/326d3c304e32645811c8/test_coverage)](https://codeclimate.com/github/simonmittag/jabba/code)
 [![SSLLabs Rating](https://img.shields.io/badge/SSLLabs-A%2B-brightgreen)](https://www.ssllabs.com/ssltest/analyze.html?d=j8a.io)