Update CHANGELOG

Author: Jake-Shadle

CHANGELOG.md

@@ -8,6 +8,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 <!-- next-header -->
 ## [Unreleased] - ReleaseDate
+### Changed
+- [PR#86](https://github.com/EmbarkStudios/spdx/pull/86) changes the license detection for GNU licenses (GPL, AGPL, LGPL, GFDL). In 0.13.0 they would be detected as their deprecated (eg. `AGPL-3.0`) variant due to the variants (root, `-only`, and `-or-later`) using the exact same license text. GNU licenses are now detected as the `<root>-or-later` version. This is an arbitrary decision, which I hope to not change, but if someone makes a convincing argument it could be.
+
 ## [0.13.0] - 2025-12-02
 ### Added
 - [PR#84](https://github.com/EmbarkStudios/spdx/pull/84) resolved [#67](https://github.com/EmbarkStudios/spdx/issues/67) by inlining the `askalono` crate to allow detection of license texts or headers from arbitrary text data. There are multiple features flags associated with this new feature.