Polish documentation and README for improved clarity and professionalism

CHANGELOG.md

@@ -1,31 +1,56 @@
-## 2.0.0 - Sep 01, 2024
+# Changelog
 
-- Require Dart 3.0.0 or higher `>=3.0.0 <4.0.0`.
+All notable changes to this project will be documented in this file.
 
-- Make `Either` a sealed class, `EitherEffect` a sealed class, and `ControlError` a final class.
-  Now you can use exhaustive switch expressions on `Either` instances.
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [2.0.0] - 2024-09-01
+
+### Changed
+
+- **BREAKING**: Require Dart SDK `>=3.0.0 <4.0.0`
+- **BREAKING**: Made `Either` a sealed class for exhaustive pattern matching
+- **BREAKING**: Made `EitherEffect` a sealed class
+- **BREAKING**: Made `ControlError` a final class
+
+### Added
+
+- ✨ **Dart 3.0 Pattern Matching**: Full support for exhaustive switch expressions
   ```dart
   final Either<String, int> either = Either.right(10);
 
-  // Use the `when` method to handle
+  // Use the `when` method
   either.when(
     ifLeft: (l) => print('Left: $l'),
     ifRight: (r) => print('Right: $r'),
-  ); // Prints Right: Either.Right(10)
+  ); // Prints: Right: Either.Right(10)
 
-  // Or use Dart 3.0 switch expression syntax 🤘
+  // Or use Dart 3.0 switch expressions 🚀
   print(
     switch (either) {
       Left() => 'Left: $either',
       Right() => 'Right: $either',
     },
-  ); // Prints Right: Either.Right(10)
+  ); // Prints: Right: Either.Right(10)
   ```
 
-## 1.0.0 - Aug 23, 2022
+## [1.0.0] - 2022-08-23
+
+### Changed
+
+- 🎉 First stable release
+- Production-ready API with comprehensive test coverage
+
+## [0.0.1] - 2021-04-27
 
-- This is our first stable release.
+### Added
 
-## 0.0.1 - Apr 27, 2021
+- Initial version created by Stagehand
+- Core `Either` monad implementation
+- Support for `Left` and `Right` types
+- Basic functional operations (map, flatMap, fold)
 
-- Initial version, created by Stagehand
+[2.0.0]: https://github.com/hoc081098/dart_either/compare/v1.0.0...v2.0.0
+[1.0.0]: https://github.com/hoc081098/dart_either/compare/v0.0.1...v1.0.0
+[0.0.1]: https://github.com/hoc081098/dart_either/releases/tag/v0.0.1