docs: update GoDoc badge URL location

- Update the GoDoc badge URL to point to the new location

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

README.md

@@ -3,7 +3,7 @@
 [![Run Tests](https://github.com/appleboy/graceful/actions/workflows/go.yml/badge.svg)](https://github.com/appleboy/graceful/actions/workflows/go.yml)
 [![codecov](https://codecov.io/gh/appleboy/graceful/branch/master/graph/badge.svg?token=zPqtcz0Rum)](https://codecov.io/gh/appleboy/graceful)
 [![Go Report Card](https://goreportcard.com/badge/github.com/appleboy/graceful)](https://goreportcard.com/report/github.com/appleboy/graceful)
-[![GoDoc](https://godoc.org/github.com/appleboy/graceful?status.svg)](https://godoc.org/github.com/appleboy/graceful)
+[![Go Reference](https://pkg.go.dev/badge/github.com/gin-contrib/graceful.svg)](https://pkg.go.dev/github.com/gin-contrib/graceful)
 
 Graceful shutdown package when a service is turned off by software function.