docs: Re-add missing cookie banner env var in build (#56889)

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)
- [ ] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Closes #ISSUE

Release Notes:

- N/A or Added/Fixed/Improved ...
1b557c7084Ben Kunkle committed on 5/15/2026, 3:04:55 PM· committed by GitHubparent61e23fd
6 files changedLine totals unavailable