docs: add changelog

CHANGELOG.md

+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+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).
+
+## [Unreleased]
+
+## [0.1.0] - 2022-03-02
+
+### Added
+
+- Dockerization for development and deployment.
+- Kubernetes architecture for deployment.
+- Solid CI pipeline.
+- DB seeding script.
+- Various QOL improvements for developers.
+
+### Changed
+
+- Backend rewritten in Node.
+
+## [0.0.1] - 2022-02-21
+
+### Added
+
+- POC by [Giovanni Moretti](https://www.giovannimoretti.it/).
+
+[unreleased]: https://gitlab.inf.unibz.it/commul/oetzi/compare/0.1.0...development
+[0.1.0]: https://gitlab.inf.unibz.it/commul/oetzi/compare/0.0.1...0.1.0
+[0.0.1]: https://gitlab.inf.unibz.it/commul/oetzi/tree/v0.0.1