message: Add release date for 0.18.0
diff: @@ -5,6 +5,8 @@ is based on [Keep a Changelog](https://keepachangelog.com).
  ## [Unreleased]
  +## [0.18.0] - 2021-01-25
  +
  ### Added
  - The enum `caf::sec` received an additional error code: `connection_closed`.
  @@ -618,7 +620,8 @@ is based on [Keep a Changelog](https://keepachangelog.com).
  - Setting the log level to `quiet` now properly suppresses any log output.
  - Configuring colored terminal output should now print colored output.
  -[Unreleased]: https://github.com/actor-framework/actor-framework/compare/0.18.0-rc.1...master
  +[Unreleased]: https://github.com/actor-framework/actor-framework/compare/0.18.0...master
  +[0.18.0]: https://github.com/actor-framework/actor-framework/releases/0.18.0
  [0.18.0-rc.1]: https://github.com/actor-framework/actor-framework/releases/0.18.0-rc.1
  [0.17.7]: https://github.com/actor-framework/actor-framework/compare/0.17.6...release/0.17
  [0.17.6]: https://github.com/actor-framework/actor-framework/releases/0.17.6
  