Add navigation item for repository archive rate limits documentation
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## Summary
Add a new navigation item to the `navigation.yml` file for the repository archive rate limits documentation page.
## Details
The documentation page `doc/administration/settings/repository_archive_rate_limits.md` was added in GitLab 18.9 but needs to be included in the navigation structure.
## Tasks
- [ ] Add navigation entry in the [navigation.yml](https://gitlab.com/gitlab-org/technical-writing/docs-gitlab-com/-/blob/main/data/en-us/navigation.yaml) file
- [ ] Place under the appropriate section (likely under Administration > Settings > Network or similar)
- [ ] Verify the navigation link works correctly on docs site
## Documentation
- Documentation page: `doc/administration/settings/repository_archive_rate_limits.md`
## Related
- https://gitlab.com/gitlab-org/security/gitlab/-/merge_requests/5620#note_3041526020
issue