add reference badge

Author: koki-develop

README.md

@@ -1,10 +1,11 @@
 # go-fzf
 
-[![GitHub release (latest by date)](https://img.shields.io/github/v/release/koki-develop/go-fzf)](https://github.com/koki-develop/go-fzf/releases/latest)
-[![GitHub Workflow Status](https://img.shields.io/github/actions/workflow/status/koki-develop/go-fzf/ci.yml?logo=github)](https://github.com/koki-develop/go-fzf/actions/workflows/ci.yml)
-[![Maintainability](https://img.shields.io/codeclimate/maintainability/koki-develop/go-fzf?style=flat&logo=codeclimate)](https://codeclimate.com/github/koki-develop/go-fzf/maintainability)
-[![Go Report Card](https://goreportcard.com/badge/github.com/koki-develop/go-fzf)](https://goreportcard.com/report/github.com/koki-develop/go-fzf)
-[![LICENSE](https://img.shields.io/github/license/koki-develop/go-fzf)](./LICENSE)
+[![Go Reference](https://pkg.go.dev/badge/github.com/koki-develop/go-fzf.svg)](https://pkg.go.dev/github.com/koki-develop/go-fzf)
+[![GitHub release (latest by date)](https://img.shields.io/github/v/release/koki-develop/go-fzf?style=flat-square)](https://github.com/koki-develop/go-fzf/releases/latest)
+[![GitHub Workflow Status](https://img.shields.io/github/actions/workflow/status/koki-develop/go-fzf/ci.yml?logo=github&style=flat-square)](https://github.com/koki-develop/go-fzf/actions/workflows/ci.yml)
+[![Maintainability](https://img.shields.io/codeclimate/maintainability/koki-develop/go-fzf?style=flat-square&logo=codeclimate)](https://codeclimate.com/github/koki-develop/go-fzf/maintainability)
+[![Go Report Card](https://goreportcard.com/badge/github.com/koki-develop/go-fzf?style=flat-square)](https://goreportcard.com/report/github.com/koki-develop/go-fzf)
+[![LICENSE](https://img.shields.io/github/license/koki-develop/go-fzf?style=flat-square)](./LICENSE)
 
 Fuzzy Finder CLI and Library.