message: docs(readme): replace irc links with discord links
diff: [![Released API docs](https://docs.rs/hyper/badge.svg)](https://docs.rs/hyper)
  [![MIT licensed](https://img.shields.io/badge/license-MIT-blue.svg)](./LICENSE)
  [![CI](https://github.com/hyperium/hyper/workflows/CI/badge.svg)](https://github.com/hyperium/hyper/actions?query=workflow%3ACI)
  +[![Discord chat][discord-badge]][discord-url]
  A **fast** and **correct** HTTP implementation for Rust.
  @@ -30,13 +31,11 @@ Both are built on top of this library.
  To get involved, take a look at [CONTRIBUTING](CONTRIBUTING.md).
  -There are two main avenues for real-time chatting about hyper: a [Gitter room][gitter]
  -and [irc.mozilla.org/hyper][irc]. They are mirrored, so choose whichever format you
  -prefer.
  -
  -[gitter]: https://gitter.im/hyperium/hyper
  -[irc]: https://kiwiirc.com/nextclient/irc.mozilla.org/#hyper
  +If you prefer chatting, there is an active community in the [Discord server][discord-url].
  ## License
  hyper is provided under the MIT license. See [LICENSE](LICENSE).
  +
  +[discord-badge]: https://img.shields.io/discord/500028886025895936.svg?logo=discord
  +[discord-url]: https://discord.gg/kkwpueZ
  