message: update changelog for v0.12.2
diff: @@ -6,7 +6,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
  -## [Unreleased]
  +## [0.12.2]
  ### Added
  - Expose `ProgramBuilder.transpile()` method to make it easier for tools to transpile programmatically. [#154](https://github.com/rokucommunity/brighterscript/issues/154)
  ### Fixed
  @@ -429,6 +429,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
  +[0.12.2]: https://github.com/rokucommunity/brighterscript/compare/v0.12.1...v0.12.2
  [0.12.1]: https://github.com/rokucommunity/brighterscript/compare/v0.12.0...v0.12.1
  [0.12.0]: https://github.com/rokucommunity/brighterscript/compare/v0.11.3...v0.12.0
  [0.11.3]: https://github.com/rokucommunity/brighterscript/compare/v0.11.2...v0.11.3
  