Add changelog.

Author: Dirbaio

embedded-hal/CHANGELOG.md

@@ -10,6 +10,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 - gpio: add `ErrorKind` enum for consistency with other traits and for future extensibility. No kinds are defined for now.
 - delay: make infallible.
+### Added
+- Added `pwm::SetDutyCycle` trait.
 
 ## [v1.0.0-alpha.9] - 2022-09-28