update changelog

Author: RobinMalfait

CHANGELOG.md

@@ -22,6 +22,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix generation of `div:not(.foo)` if `.foo` is never defined ([#7815](https://github.com/tailwindlabs/tailwindcss/pull/7815))
 - Allow for custom properties in `rgb`, `rgba`, `hsl` and `hsla` colors ([#7933](https://github.com/tailwindlabs/tailwindcss/pull/7933))
 - Remove autoprefixer as explicit peer-dependency to avoid invalid warnings in situations where it isn't actually needed ([#7949](https://github.com/tailwindlabs/tailwindcss/pull/7949))
+- Types: allow for arbitrary theme values (for 3rd party plugins) ([#7926](https://github.com/tailwindlabs/tailwindcss/pull/7926))
 
 ### Changed