docs: Clarify that `"..."` enables all other registered language servers (#51427)

Closes #51416

Before you mark this PR as ready for review, make sure that you have:

- [ ] Added a solid test coverage and/or screenshots from doing manual
testing
- [ ] Done a self-review taking into account security and performance
aspects
- [ ] Aligned any UI changes with the [UI
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)

Release Notes:

- N/A
b15a8c1e5eJustin Su committed on 3/13/2026, 12:05:27 AM· committed by GitHubparenta07d0f4
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