[DOCUMENTATION] port settings for REST api in docker compose file.

On documentation page for RESTful API V2 it will be helpful if adjusted docker compose file with additional port property is mentioned in the area of [Enable RESTful Services](https://iotdb.apache.org/UserGuide/latest/API/RestServiceV2.html#enable-restful-services).

```
ports:
- "6667:6667"
- "18080:18080"
```

When users want to enable REST service, an additional port has to be added in the docker compose file.

Best regards
André

打开链接的 Enable RESTful Services 部分中的 RESTful API V2 文档，并检查 Docker Compose 示例。将额外的 18080:18080 端口与现有的 6667:6667 映射一并记录，然后验证示例是否说明了启用 REST 服务所需的端口。

由索引模型根据 Issue 内容生成。