- Enforce that an option declaration has a "defaultText" if and only if the
type of the option derives from "package", "packageSet" or "nixpkgsConfig"
and if a "default" attribute is defined.
- Enforce that the value of the "example" attribute is wrapped with "literalExample"
if the type of the option derives from "package", "packageSet" or "nixpkgsConfig".
- Warn if a "defaultText" is defined in an option declaration if the type of
the option does not derive from "package", "packageSet" or "nixpkgsConfig".
- Warn if no "type" is defined in an option declaration.
Having configuration.nix generation hidden underneath nixos-option
never made sense, also given that there was another command to
generate part of the configuration (nixos-hardware-scan). Now
nixos-generate-config produces both configuration.nix and
hardware-configuration.nix. The latter is overwritten while the
former is not.