update changelog for release

CHANGELOG.md

@@ -5,6 +5,8 @@ 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][]
+
+## [0.8.0][] - 2018-02-17
 ### Breaking
 -   The `BYTIME` option of `RRULE`s in the iCalendar output is now `X-BYTIME` to better follow the standard's extensions policy
 
@@ -71,7 +73,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ## 0.0.1 - 2017-09-08
 ### Initial release
 
-[Unreleased]: https://github.com/peek-travel/cocktail/compare/0.7.0...HEAD
+[Unreleased]: https://github.com/peek-travel/cocktail/compare/0.8.0...HEAD
+[0.8.0]: https://github.com/peek-travel/cocktail/compare/0.7.0...0.8.0
 [0.7.0]: https://github.com/peek-travel/cocktail/compare/0.6.0...0.7.0
 [0.6.0]: https://github.com/peek-travel/cocktail/compare/0.5.3...0.6.0
 [0.5.3]: https://github.com/peek-travel/cocktail/compare/0.5.2...0.5.3