[suggestion] Support TOML configuration

[0x009922]

Feature request

Probably, use only TOML, because supporting both JSON and TOML might overcomplicate documentation (e.g. the need to provide examples for both formats). Focusing on a single format might net a better docs quality.

Motivation

TOML is a friendlier configuration format than JSON and even JSON5. It is the standard Rust configuration format.

[0x009922]

Closed by #4239