Update changelog for recent changes since 1.1.1

CHANGELOG.md

@@ -7,7 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-- (Add unreleased changes here)
+- Clarified that `acquire()` must provide ordering guarantees
+- Updated atomic-polyfill reference to point to portable-atomic instead
+- Improved documentation for `Mutex` example
+- Added list of some known implementations
 
 ## [v1.1.1] - 2022-09-13
 
@@ -126,4 +129,4 @@ If you're seeing a linker error like `undefined symbol: _critical_section_1_0_ac
 [v0.2.3]: https://github.com/rust-embedded/critical-section/compare/v0.2.2...v0.2.3
 [v0.2.2]: https://github.com/rust-embedded/critical-section/compare/v0.2.1...v0.2.2
 [v0.2.1]: https://github.com/rust-embedded/critical-section/compare/v0.2.0...v0.2.1
-[v0.2.0]: https://github.com/rust-embedded/critical-section/compare/v0.1.0...v0.2.0
+[v0.2.0]: https://github.com/rust-embedded/critical-section/compare/v0.1.0...v0.2.0