Fix Mixtral: Docstring uses consistent 'top_k_index' and 'top_k_weights' in MixtralSparseMoeBlock

[ShivanshTiwari1]

What does this PR do?

This PR resolves a minor documentation inconsistency found in the MixtralSparseMoeBlock.forward method located in src/transformers/models/mixtral/modular_mixtral.py.

The function definition correctly uses the parameters top_k_index and top_k_weights, but the docstring incorrectly referenced them as selected_experts and routing_weights.

This update ensures the documentation is accurate, which is crucial for code clarity and for any models that inherit this MoE block.

---

Fixes #41984

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you read the contributor guideline, Pull Request section?
• Was this discussed/approved via a Github issue or the forum? Please add a link to it if that's the case. (The linked issue shows approval.)
• Did you make sure to update the documentation with your changes? (The change is the documentation update itself.)
• Did you write any new necessary tests?

Who can review?

@ArthurZucker (As tagged in the original issue thread)

[Rocketknight1]

Hi @ShivanshTiwari1 the fixes look okay, but there are a lot of unrelated style changes in the code! Try to revert those, or do pip install -e .[quality] to get the style tools yourself and run make fixup or make style to ensure the code matches our formatting rules.

[github-actions]

[For maintainers] Suggested jobs to run (before merge)

run-slow: mixtral