Update changelog for 0.1.1 release

CHANGELOG.md

@@ -4,7 +4,7 @@ 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]
+## [0.1.1] - 2018-04-29
 ### Added
 - `Scratchpad::static_new()` function for creating scratchpads backed by
   static arrays without having to pass array instances as function parameters.
@@ -39,4 +39,4 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Added
 - Initial release.
 
-[Unreleased]: https://github.com/okready/scratchpad/compare/0.1.0...HEAD
+[0.1.1]: https://github.com/okready/scratchpad/compare/0.1.0...0.1.1