RFC 0166 FCP: Nix formatting

The Final Comment Period for RFC 166 has started! Barring any blocking issues it will be merged in 13 days (the next time the steering committee meets) on 2024-03-04T23:00:00Z

The shepherd team will have a final meeting a day before that on 2024-03-04T19:00:00Z in https://meet.zrh.init7.net/rfc-101 to discuss any potential comments brought up during FCP, how to address them, or whether FCP needs to be canceled and retried later.