docs: Add/update CHANGELOG.

Author: drupol

CHANGELOG.md

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+# 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).
+
+## [1.0.0](https://github.com/loophp/phpunit-iterable-assertions/compare/0.0.1...1.0.0)
+
+### Commits
+
+- Initial set of files [`d3ba183`](https://github.com/loophp/phpunit-iterable-assertions/commit/d3ba183645d47909221b786b13f429bc9c5d9304)
+
+## 0.0.1 - 2021-12-15
+
+### Commits
+
+- Initial commit. [`9b961d1`](https://github.com/loophp/phpunit-iterable-assertions/commit/9b961d13c546fdd7a11a22bae208fd9287a2e9c1)