[#23] Updated CHANGELOG

Author: ryu1kn

CHANGELOG.md

@@ -5,6 +5,11 @@ 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]
+### Added
+- Made TypeScript type definitions accessible. Thanks to @coyotte508.
+  [PR #23](https://github.com/ryu1kn/csv-writer/pull/23)
+
 ## [1.2.0] - 2018-08-22
 ### Added
 - CSV records are now not limited to an array but can be an iterable object. Thanks to @pineapplemachine.