Updated badge.

Author: Kugelschieber

README.md

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 # ISO 639-1
 
-[![GoDoc](https://godoc.org/github.com/emvi/iso-639-1?status.svg)](https://godoc.org/github.com/emvi/iso-639-1)
+[![Go Reference](https://pkg.go.dev/badge/github.com/emvi/iso-639-1?status.svg)](https://pkg.go.dev/github.com/emvi/iso-639-1?status)
 [![CircleCI](https://circleci.com/gh/emvi/iso-639-1.svg?style=svg)](https://circleci.com/gh/emvi/iso-639-1)
 [![Go Report Card](https://goreportcard.com/badge/github.com/emvi/iso-639-1)](https://goreportcard.com/report/github.com/emvi/iso-639-1)
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