add goreport badge

Author: Oleg Sucharevich

README.md

@@ -2,6 +2,7 @@
 
 [![Codefresh build status]( https://g.codefresh.io/api/badges/pipeline/codefresh-inc/codefresh-io%2Fgo-sdk%2Fgo-sdk?type=cf-1)]( https://g.codefresh.io/public/accounts/codefresh-inc/pipelines/codefresh-io/go-sdk/go-sdk) 
 [![GoDoc](https://godoc.org/github.com/codefresh-io/go-sdk?status.svg)](https://godoc.org/github.com/codefresh-io/go-sdk)
+[![Go Report Card](https://goreportcard.com/badge/github.com/codefresh-io/go-sdk)](https://goreportcard.com/report/github.com/codefresh-io/go-sdk)
 
 # Start