Add missing changelog entry (#14686)

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Author: RobinMalfait

CHANGELOG.md

@@ -7,7 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-- Nothing yet!
+### Fixed
+
+- _Upgrade (experimental)_: Speed up template migrations ([#14679](https://github.com/tailwindlabs/tailwindcss/pull/14679))
 
 ## [4.0.0-alpha.27] - 2024-10-15