Merge pull request #22 from hashicorp/radditude/rename-default-branch

update references to default branch

README.md

@@ -1,7 +1,7 @@
 # go-slug
 
 [![Build Status](https://github.com/hashicorp/go-slug/actions/workflows/test.yml/badge.svg)](https://github.com/hashicorp/go-slug/actions/workflows/test.yml)
-[![GitHub license](https://img.shields.io/github/license/hashicorp/go-slug.svg)](https://github.com/hashicorp/go-slug/blob/master/LICENSE)
+[![GitHub license](https://img.shields.io/github/license/hashicorp/go-slug.svg)](https://github.com/hashicorp/go-slug/blob/main/LICENSE)
 [![GoDoc](https://godoc.org/github.com/hashicorp/go-slug?status.svg)](https://godoc.org/github.com/hashicorp/go-slug)
 [![Go Report Card](https://goreportcard.com/badge/github.com/hashicorp/go-slug)](https://goreportcard.com/report/github.com/hashicorp/go-slug)
 [![GitHub issues](https://img.shields.io/github/issues/hashicorp/go-slug.svg)](https://github.com/hashicorp/go-slug/issues)