Merge pull request #67 from hashicorp/godoc-badge

Add godoc.org badge to README

Author: justincampbell

README.md

@@ -1,5 +1,6 @@
 # Versioning Library for Go
 [![Build Status](https://circleci.com/gh/hashicorp/go-version/tree/master.svg?style=svg)](https://circleci.com/gh/hashicorp/go-version/tree/master)
+[![GoDoc](https://godoc.org/github.com/hashicorp/go-version?status.svg)](https://godoc.org/github.com/hashicorp/go-version)
 
 go-version is a library for parsing versions and version constraints,
 and verifying versions against a set of constraints. go-version