Update changelog

Author: thetek42

CHANGELOG.md

@@ -47,6 +47,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `DefaultProgressCallback` which implements `ProgressCallbacks` but all methods are no-ops (#904)
 - `ProgressCallbacks` now has a `verifying` method to notify when post-flash checksum checking has begun (#908)
 - Implement `From<Connection> for Port` and both `From<Flasher> for Connection` and `Port` conversions (#915)
+- Add support for serial port configuration files. (#777)
+- Add support for secure padding for save-image (#876)
 
 ### Changed