I needed to run the docs locally and ran into this error when following
the [docs
README.md](https://github.com/zed-industries/zed/blob/main/docs/README.md).

```
Error: Found 27 errors in docs
2026-04-01 10:15:39 [ERROR] (mdbook::utils): Error: The "zed_docs_preprocessor" preprocessor exited unsuccessfully with exit status: 1 status
```

It turns out I needed to run `script/generate-action-metadata` first.
This PR adds that step to the doc.

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 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

Closes #ISSUE

Release Notes:

- N/A