add changelog

Author: bdebinska

CHANGELOG.md

@@ -0,0 +1,20 @@
+# 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/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+Unreleased changes will be displayed here upon implementation.
+
+## [0.2.0] - 2025-08-13
+
+### Added
+
+- [JSV](https://hexdocs.pm/jsv/JSV.html)-compatible JsonSchema definitions for `format` and `defaults` as
+  `ValueFormatter.Schema.Format` and `ValueFormatter.Schema.DefaultFormats`, respectively.
+
+[unreleased]: https://github.com/box-id/value_formatters/compare/0.2.0...HEAD
+[0.2.0]: https://github.com/box-id/value_formatters/releases/tag/0.2.0