message: Update warning text
diff: [![Documentation](https://docs.rs/nats/badge.svg)](https://docs.rs/nats/)
  [![Build Status](https://travis-ci.org/nats-io/nats.rs.svg?branch=master)](http://travis-ci.org/nats-io/nats.rs)
  -Warning: as of version 0.4.0, this crate has been rewritten, and several public
  -APIs have changed. Please see the [docs](https://docs.rs/nats), the [new
  +Warning: as of version 0.4.0, this crate has switched code bases
  +to a Synadia (official maintainers of NATS.io) implementation.
  +Please see the [new API docs](https://docs.rs/nats), the [new
  repo](https://github.com/nats-io/nats.rs), and [the
  changelog](https://github.com/nats-io/nats.rs/blob/master/CHANGELOG.md) for
  details.
  