[Docs] Complete missing Llama4 configuration docs (#43460)
* [Docs]: Complete missing docs for Llama4Config
* fix: Apply ruff formatting again
* [Docs] Fix type hints (moe_layers list, floats) and style
* [Docs] Updated docstring to describe the functional impact of certain parameters instead of raw definition
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Co-authored-by: Cyril Vallez <cyril.vallez@huggingface.co>
