Add Go reference badge

Author: raphink

README.md

@@ -1,6 +1,7 @@
 # instruqt-go
 
 [![Go Report Card](https://goreportcard.com/badge/github.com/isovalent/instruqt-go)](https://goreportcard.com/report/github.com/isovalent/instruqt-go)
+[![Go Reference](https://pkg.go.dev/badge/github.com/isovalent/instruqt-go.svg)](https://pkg.go.dev/github.com/isovalent/instruqt-go)
 [![License: Apache 2.0](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](LICENSE)
 
 `instruqt-go` is a Go client library for interacting with the Instruqt platform. It provides a simple and convenient way to programmatically access Instruqt's APIs, manage content, retrieve user data and track information.