Update CHANGELOG

Author: Jake-Shadle

CHANGELOG.md

@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 <!-- next-header -->
 ## [Unreleased] - ReleaseDate
+### Added
+- [PR#26](https://github.com/EmbarkStudios/cfg-expr/pull/26) added `Expression::original` to get the original string the expression was parsed from. Thanks [@gdesmott](https://github.com/gdesmott)!
+
 ## [0.7.3] - 2021-03-16
 ### Added
 - [PR#25](https://github.com/EmbarkStudios/cfg-expr/pull/25) added `Clone` for `Expression`. Thanks [@gdesmott](https://github.com/gdesmott)!