The config directory stores configuration files for various apps, utils and systems.

Generic configs which are used across all systems (e.g. .gitconfig, .bashrc, .wgetrc)
are stored in the root of the config directory, whereas files which are only used on
certain systems (like MacOS) or by certain applications (like Firefox's user.js) are
kept in category-specific directories (e.g. macos, desktop-apps, etc).