add changelog for 4.2.0

CHANGELOG.md

@@ -1,11 +1,18 @@
 # Changelog
+
 All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased][unreleased]
 
+## [4.2.0] - 2018-12-11
+
+### Added
+
+- `existingConfig` method for site installs (which sets `--existing-config` in the drush call)
+
 ## [4.1.0] - 2018-09-11
 
 ### Added
@@ -117,7 +124,7 @@ Release for Robo >=0.5 (not compatible with 0.4.*!).
 ### Added
 - Initial commit
 
-[unreleased]: https://github.com/boedah/robo-drush/compare/3.1.1...HEAD
+[unreleased]: https://github.com/boedah/robo-drush/compare/4.2.0...HEAD
 [1.0.1]: https://github.com/boedah/robo-drush/compare/1.0.0...1.0.1
 [1.0.2]: https://github.com/boedah/robo-drush/compare/1.0.1...1.0.2
 [1.0.3]: https://github.com/boedah/robo-drush/compare/1.0.2...1.0.3
@@ -132,3 +139,4 @@ Release for Robo >=0.5 (not compatible with 0.4.*!).
 [3.1.1]: https://github.com/boedah/robo-drush/compare/3.1.0...3.1.1
 [4.0.0]: https://github.com/boedah/robo-drush/compare/3.1.1...4.0.0
 [4.1.0]: https://github.com/boedah/robo-drush/compare/4.0.0...4.1.0
+[4.2.0]: https://github.com/boedah/robo-drush/compare/4.1.0...4.2.0