migrate: Remove archive tutorials (migrated to datajoint-docs)

- dj-top.ipynb → datajoint-docs 04-queries.ipynb (dj.Top section)
- json.ipynb → datajoint-docs advanced/json-type.ipynb

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: dimitri-yatsenko