message: Add gen-tsd CHANGELOG entry
diff: @@ -4,7 +4,8 @@ All notable changes to this project will be documented in this file.
  The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
  and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
  -<!-- ## [Unreleased] -->
  +## [Unreleased]
  +* Fix missing `source-map-support` dependency.
  <!-- Add new, unreleased changes here. -->
  ## [1.6.0] - 2018-12-05
  