2.2.0

Minimum PHP version is now 8.1. Added library documentation generated via phpDocumentor.

What's Changed

• Bump PHP to 8.1 minimum by @mondrake in #80
• Update code to PHP 8 by @mondrake in #81
• Add code documentation with GitHub Pages and phpDocumentor by @mondrake in #82
• Adjust documentation by @mondrake in #83
• Fix BaseMap::$instance BC issue by @mondrake in #85

Full Changelog: 2.1.2...2.2.0