update CHANGELOG.md for 0.2.0

CHANGELOG.md

@@ -5,8 +5,15 @@ 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]
+
+## [0.2.0] - 2018-06-07
+### Added
+- grayscale support
+
 ### Fixed
 - reduced memory footprint on complex files
+- improved speed
+- decoding image header and then image caused an error
 
 ## [0.1.0] - 2017-12-23
 ### Added
@@ -18,7 +25,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - pixel data decoding
 
 ### Fixed
-- Near zero decoding for negative numbers
+- near zero decoding for negative numbers
 
 
 ## [0.0.2] - 2017-10-14
@@ -43,6 +50,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - readme file
 - license
 
-[Unreleased]: https://github.com/dgriffen/flif.rs/compare/v0.1.0...HEAD
+[Unreleased]: https://github.com/dgriffen/flif.rs/compare/v0.2.0...HEAD
 [0.0.2]: https://github.com/dgriffen/flif.rs/compare/v0.0.1...v0.0.2
 [0.1.0]: https://github.com/dgriffen/flif.rs/compare/v0.0.2...v0.1.0
+[0.2.0]: https://github.com/dgriffen/flif.rs/compare/v0.1.0...v0.2.0