Remove search_on_input from docs (#52435)

## Context

<img width="1610" height="394" alt="CleanShot 2026-03-25 at 15 32 24@2x"
src="https://github.com/user-attachments/assets/704753d5-17c0-4857-8599-718b310211c8"
/>


Although search_on_input is a merged feature, it doesn't look like it's
live yet. As a result, some people might be trying to activate the
feature without success.

This commit removes its reference from the docs.

## How to Review

- Check if the feature is live before merging

## Self-Review Checklist

<!-- Check before requesting review: -->
- [X] I've reviewed my own diff for quality, security, and reliability
- [X] Unsafe blocks (if any) have justifying comments
- [X] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [X] Tests cover the new/changed behavior
- [X] Performance impact has been considered and is acceptable

Release Notes:

- N/A
f84af034baHilder Santos committed on 3/25/2026, 6:41:37 PM· committed by GitHubparent1fa7f1a
2 files changedLine totals unavailable