update changelog

Author: RobinMalfait

CHANGELOG.md

@@ -22,6 +22,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Hide internal fields from completions in `matchUtilities` ([#18820](https://github.com/tailwindlabs/tailwindcss/pull/18820))
 - Ignore `.vercel` folders by default (can be overridden by `@source …` rules) ([#18855](https://github.com/tailwindlabs/tailwindcss/pull/18855))
 - Consider variants starting with `@-` to be invalid (e.g. `@-2xl:flex`) ([#18869](https://github.com/tailwindlabs/tailwindcss/pull/18869))
+- Do not allow custom variants to start with a `-` ([#18867](https://github.com/tailwindlabs/tailwindcss/pull/18867))
 - Upgrade: Migrate `aria` theme keys to `@custom-variant` ([#18815](https://github.com/tailwindlabs/tailwindcss/pull/18815))
 - Upgrade: Migrate `data` theme keys to `@custom-variant` ([#18816](https://github.com/tailwindlabs/tailwindcss/pull/18816))
 - Upgrade: Migrate `supports` theme keys to `@custom-variant` ([#18817](https://github.com/tailwindlabs/tailwindcss/pull/18817))