build: update docker config and refine s3s region handling (#1976)

Co-authored-by: houseme <housemecn@gmail.com>

.docker/mqtt/README.md

@@ -0,0 +1,30 @@
+# MQTT Broker (EMQX)
+
+This directory contains the configuration for running an EMQX MQTT broker, which can be used for testing RustFS's MQTT integration.
+
+## 🚀 Quick Start
+
+To start the EMQX broker:
+
+```bash
+docker compose up -d
+```
+
+## 📊 Access
+
+- **Dashboard**: [http://localhost:18083](http://localhost:18083)
+- **Default Credentials**: `admin` / `public`
+- **MQTT Port**: `1883`
+- **WebSocket Port**: `8083`
+
+## 🛠️ Configuration
+
+The `docker-compose.yml` file sets up a single-node EMQX instance.
+
+- **Persistence**: Data is not persisted by default (for testing).
+- **Network**: Uses the default bridge network.
+
+## 📝 Notes
+
+- This setup is intended for development and testing purposes.
+- For production deployments, please refer to the official [EMQX Documentation](https://www.emqx.io/docs/en/latest/).