Undocumented nvidia option in akmods module

[flexagoon]

The akmods module has an nvidia option which is implemented in the Rust code of the BlueBuild CLI instead of the module code, and isn't documented anywhere.

https://github.com/blue-build/cli/blob/f83cddfbe079fdf770b951af4c8765a5092146b9/recipe/src/module.rs#L133

This option should be documented

[flexagoon]

Upd: the option is also not included in the module schema, so the Containerfile generation fails