update changelog

Author: RobinMalfait

CHANGELOG.md

@@ -29,6 +29,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix crash when watching renamed files on FreeBSD ([#12193](https://github.com/tailwindlabs/tailwindcss/pull/12193))
 - Allow plugins from a parent document to be used in an iframe ([#12208](https://github.com/tailwindlabs/tailwindcss/pull/12208))
 - Add types for `tailwindcss/nesting` ([#12269](https://github.com/tailwindlabs/tailwindcss/pull/12269))
+- Improve automatic `var` injection for properties that accept a `<dashed-ident>` ([#12236](https://github.com/tailwindlabs/tailwindcss/pull/12236))
 
 ### Added