docs: update CHANGELOG for v2.0.0 release

Author: mfazrinizar

CHANGELOG.md

@@ -1,8 +1,23 @@
-## 1.0.0
+## 2.0.0
 
-- Initial version.
-- Update dependencies and refactor from discontinued secure_dotenv. 
+- **BREAKING**: Updated `pointycastle` dependency from `^3.9.1` to `^4.0.0`.
+- **Security**: Removed insecure `String.fromEnvironment()` / `--dart-define` pattern from examples (addresses [#2](https://github.com/mfazrinizar/flutter_secure_dotenv/issues/2)).
+- Added `SECURITY.md` with detailed encryption key management guidance.
+- Updated README with security warnings and recommended key provisioning approaches.
+- Updated `lints` to `^6.1.0`, `test` to `^1.29.0`.
+- Enhanced test coverage from 8 to 43 tests (padding, random byte generation, edge cases).
+- Added fully working Flutter example app with hardcoded key + gitignore approach.
+- Added 100% `public_member_api_docs` coverage.
+- Made `AESCBCEncrypter` non-instantiable (static-only utility class).
+- Added library-level dartdoc comments.
+- Added GitHub Actions CI workflow.
+- Added `CONTRIBUTING.md`.
 
 ## 1.0.1
 
-- Refactor README and example.
+- Refactor README and example.
+
+## 1.0.0
+
+- Initial version.
+- Update dependencies and refactor from discontinued secure_dotenv.