add changelog

CHANGELOG.md

@@ -5,6 +5,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+- #678 - Add optional `target.{target}.dockerfile[.file]`, `target.{target}.dockerfile.context` and `target.{target}.dockerfile.build-args` to invoke docker/podman build before using an image.
+- #678 - Add `target.{target}.pre-build` config for running commands before building the image.
 - #681 - Warn on unknown fields and confusable targets
 - #665 - when not using [env.volumes](https://github.com/cross-rs/cross#mounting-volumes-into-the-build-environment), mount project in /project
 - #624 - Add `build.default-target`