Update changelog

Author: adamwathan

CHANGELOG.md

@@ -11,6 +11,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Add `background-origin` utilities ([#4117](https://github.com/tailwindlabs/tailwindcss/pull/4117))
 
+## [2.1.2] - 2021-04-23
+
+### Fixed
+
+- Fix issue where JIT engine would generate the wrong CSS when using PostCSS 7 ([#4078](https://github.com/tailwindlabs/tailwindcss/pull/4078)
+
 ## [2.1.1] - 2021-04-05
 
 ### Fixed
@@ -1356,7 +1362,8 @@ No release notes
 
 - Everything!
 
-[unreleased]: https://github.com/tailwindlabs/tailwindcss/compare/v2.1.1...HEAD
+[unreleased]: https://github.com/tailwindlabs/tailwindcss/compare/v2.1.2...HEAD
+[2.1.2]: https://github.com/tailwindlabs/tailwindcss/compare/v2.1.1...v2.1.2
 [2.1.1]: https://github.com/tailwindlabs/tailwindcss/compare/v2.1.0...v2.1.1
 [2.1.0]: https://github.com/tailwindlabs/tailwindcss/compare/v2.0.4...v2.1.0
 [2.0.4]: https://github.com/tailwindlabs/tailwindcss/compare/v2.0.3...v2.0.4