Document `hidden_files` setting (#64403)

## Objective

While suggesting #64399, I realized `hidden_files` didn’t have an entry
in the settings reference. This PR fills that gap.

## Testing

Checked the descriptions against the implementation and existing tests.

## Self-Review Checklist:

- [x] I’ve reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content adheres to Zed’s UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

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Release Notes:

- N/A
19096d4c87Dom Porada committed on 9/17/2026, 5:51:22 PM· committed by GitHubparentc24e309
2 files changedLine totals unavailable