update changelog

Improve wording a bit.

Author: RobinMalfait

CHANGELOG.md

@@ -14,7 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Validate `theme()` works in arbitrary values ([#6852](https://github.com/tailwindlabs/tailwindcss/pull/6852))
 - Properly detect `theme()` value usage in arbitrary properties ([#6854](https://github.com/tailwindlabs/tailwindcss/pull/6854))
 - Improve collapsing of duplicate declarations ([#6856](https://github.com/tailwindlabs/tailwindcss/pull/6856))
-- Remove the watching context ([#6858](https://github.com/tailwindlabs/tailwindcss/pull/6858))
+- Remove support for `TAILWIND_MODE=watch` ([#6858](https://github.com/tailwindlabs/tailwindcss/pull/6858))
 
 ## [3.0.8] - 2021-12-28