Update CHANGELOG

Author: Jake-Shadle

CHANGELOG.md

@@ -6,6 +6,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 <!-- next-header -->
 ## [Unreleased] - ReleaseDate
+### Added
+- [PR#25](https://github.com/EmbarkStudios/cfg-expr/pull/25) added `Clone` for `Expression`. Thanks [@gdesmott](https://github.com/gdesmott)!
 ## [0.7.2] - 2021-03-16
 ### Added
 - [PR#23](https://github.com/EmbarkStudios/cfg-expr/pull/23) added a `PartialEq` implementation for `Expression`, primarily for cases where an `Expression` is stored in a type that itself requires `PartialEq`. This is only a simple syntactical equality check. Thanks [@gdesmott](https://github.com/gdesmott)!