docs: update changelog

CHANGELOG.md

@@ -1 +1,13 @@
-Coming soon.
+# Changelog
+
+All notable changes to Bandsnatch 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).
+
+# [0.1.0] - 2022-10-02
+
+Initial public release of Bandsnatch.
+
+[0.1.0]: https://github.com/Ovyerus/bandsnatch/releases/tag/v0.1.0