docs: update coordination documentation with configurable settings

- Add section 10: Configurable Coordination (env vars + per-instance)
- Document all 4 env vars with descriptions and defaults
- Document per-instance override via coordinationSettings JSON field
- Add presets table for common scenarios (A/B/C/D)
- Document GET /chatbot/manage/status response with config
- Document required DB migration
- Update cosas-pendietnes.md with completed coordination config items
- Renumber sections 11-13
- Fix branch name reference

Author: sosamilton