add missing changelog entries

Author: RobinMalfait

CHANGELOG.md

@@ -14,6 +14,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Ensure to transpile the PostCSS Nesting plugin (tailwindcss/nesting) ([#7080](https://github.com/tailwindlabs/tailwindcss/pull/7080))
+- Improve various warnings ([#7118](https://github.com/tailwindlabs/tailwindcss/pull/7118))
+- Fix grammatical mistake ([cca5a38](https://github.com/tailwindlabs/tailwindcss/commit/cca5a3804e1d3ee0214491921e1aec35bf62a813))
 
 ## [3.0.15] - 2022-01-15