Fix minor style error in Spanish docs
# What does this PR do?

This PR is a minor fix of style since CircleCI is red due to style. FYI I did this in clean environment

```
pip install hf-doc-builder -U
pip install -e ".[dev]"
make style
```

Part of #15947
_The documentation is not available anymore as the PR was closed or merged._<|||||>cc @sgugger <|||||>Thank you very much @osanseviero! I was missing this part: `pip install -e ".[dev]"`. Was really frustrating but a lesson learned. 🚀