Merge #446

446: Update changelog after #442 r=Dirbaio a=eldruin

This was forgotten in #442 

Co-authored-by: Diego Barrios Romero <eldruin@gmail.com>

Author: bors[bot]

embedded-hal-async/CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+### Added
+- Added a `serial::Write` trait.
+
 ### Changed
 - delay: make infallible.