fix the link to go doc to go to v2 (#237)

[ci skip]

README.md

@@ -6,7 +6,7 @@ Nkeys use [Ed25519](https://ed25519.cr.yp.to/) to provide authentication of JWT
 [![License Apache 2](https://img.shields.io/badge/License-Apache2-blue.svg)](https://www.apache.org/licenses/LICENSE-2.0)
 [![ReportCard](https://goreportcard.com/badge/github.com/nats-io/jwt)](https://goreportcard.com/report/nats-io/jwt)
 [![Build Status](https://travis-ci.com/nats-io/jwt.svg?branch=master)](https://travis-ci.com/github/nats-io/jwt)
-[![GoDoc](https://godoc.org/github.com/nats-io/jwt?status.png)](https://godoc.org/github.com/nats-io/jwt)
+[![GoDoc](https://godoc.org/github.com/nats-io/jwt?status.png)](https://godoc.org/github.com/nats-io/jwt/v2)
 [![Coverage Status](https://coveralls.io/repos/github/nats-io/jwt/badge.svg?branch=main)](https://coveralls.io/github/nats-io/jwt?branch=main)
 ```go
 // create an operator key pair (private key)