tox only supports INI configuration and if one desires putting that in the standard pyproject.toml file then it must be a multi-line string containing the INI config which would preclude syntax highlighting. Hatch allows for TOML-based config just like most other tools in the Python ecosystem.
Tox now supports "native" TOML config since 2024-09-30: https://tox.wiki/en/latest/changelog.html#v4-21-0-2024-09-30
Oh my, I didn't realise it was such a recent change! Still would be nice to mention.
Something like...
Or you could just remove the mention of Tox to avoid the above statement getting stale.