Publish `Changelog`

[azriel1rf]

The project currently lacks a formally published changelog. A well-maintained changelog is essential for users and contributors to track changes, updates, and fixes over time.

Task

• Create a changelog that documents the historical and upcoming changes in a clear and structured format.
• Publish the changelog in a suitable section of the project repository, such as under a CHANGELOG.md file or a dedicated section in the documentation.

Optional Task

• Once the changelog is published, consider updating the Changelog field in the [project.urls] section of pyproject.toml to link directly to the changelog. Current placeholder URL is https://github.com/HenryRLee/PokerHandEvaluator/tags.

Relevant Files

• Potentially new CHANGELOG.md or updates to existing documentation files.