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 `pre-build` config for running commands before building the image.
 - #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`
 - #670 - Use serde for deserialization of Cross.toml