Update changelog

Author: thecrypticace

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Show warnings for invalid content config ([#7065](https://github.com/tailwindlabs/tailwindcss/pull/7065))
+
 ### Fixed
 
 - Fix consecutive builds with at apply producing different CSS ([#6999](https://github.com/tailwindlabs/tailwindcss/pull/6999))