Update changelog for release

CHANGELOG.md

@@ -5,6 +5,10 @@ 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]
+## [0.5.1]
+### Fixed
+- Fixed front end to allow ppn control to remain blank
+
 ## [0.5.0]
 ### Added
 - Added control to select number of CPUs
@@ -55,7 +59,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Added
 - Initial release!
 
-[Unreleased]: https://github.com/OSC/bc_osc_matlab/compare/v0.5.0...HEAD
+[Unreleased]: https://github.com/OSC/bc_osc_matlab/compare/v0.5.1...HEAD
+[0.5.1]: https://github.com/OSC/bc_osc_matlab/compare/v0.5.0...v0.5.1
 [0.5.0]: https://github.com/OSC/bc_osc_matlab/compare/v0.4.0...v0.5.0
 [0.4.0]: https://github.com/OSC/bc_osc_matlab/compare/v0.3.0...v0.4.0
 [0.3.0]: https://github.com/OSC/bc_osc_matlab/compare/v0.2.0...v0.3.0