docs(scanner): document runtime scanner controls (#3339)

* docs(scanner): document runtime scanner controls

* docs(scanner): split English and Chinese README

---------

Co-authored-by: Henry Guo <marshawcoco@users.noreply.github.com>
Co-authored-by: majinghe <42570491+majinghe@users.noreply.github.com>

crates/scanner/README.md

@@ -1,36 +1,28 @@
 # RustFS Scanner
 
-RustFS Scanner 提供了数据完整性检查、健康监控和存储分析等扫描功能。
+RustFS Scanner is the background maintenance scan loop. It handles usage
+accounting, lifecycle expiry and transition admission, bucket replication repair
+admission, scanner-driven heal/bitrot checks, and namespace alerts.
 
-## 功能特性
+For operator-facing runtime controls, status fields, and tuning workflows, see
+[Scanner Runtime Controls](../../docs/operations/scanner-runtime-controls.md).
 
-- 数据完整性扫描
-- 健康监控
-- 存储分析
-- 可扩展的扫描框架
+Chinese documentation is available in [README.zh-CN.md](README.zh-CN.md).
 
-## 使用示例
+## Development
 
-```rust
-use rustfs_scanner::ScannerError;
-
-// TODO: 添加使用示例
-```
-
-## 开发
-
-### 构建
+### Build
 
 ```bash
 cargo build --package rustfs-scanner
 ```
 
-### 测试
+### Test
 
 ```bash
 cargo test --package rustfs-scanner
 ```
 
-## 许可证
+## License
 
 Apache License 2.0

crates/scanner/README.zh-CN.md

@@ -0,0 +1,26 @@
+# RustFS Scanner
+
+RustFS Scanner 是后台维护扫描循环，负责用量统计、生命周期过期和分层转移准入、桶复制修复准入、scanner 发起的 heal/bitrot 检查，以及命名空间告警。
+
+面向运维人员的运行时控制项、状态字段和调参流程，请参考
+[Scanner Runtime Controls](../../docs/operations/scanner-runtime-controls.md)。
+
+英文文档请参考 [README.md](README.md)。
+
+## 开发
+
+### 构建
+
+```bash
+cargo build --package rustfs-scanner
+```
+
+### 测试
+
+```bash
+cargo test --package rustfs-scanner
+```
+
+## 许可证
+
+Apache License 2.0