docs(multi-service): add English multi-service documentation

- Add basic setup with Promise.all for concurrent routers
- Add cache, event bus, and session store sharing examples
- Add deployment section with Docker and Nginx reverse proxy
- Add middleware section with shared logger, error handler, wrapMiddleware, and OpenTelemetry
- Add router isolation and directory structure sections
- Add scaling out section for extracting services to separate processes

Author: NeaByteLab