Doc: executor manager updated docker version (#11946)

### What problem does this PR solve?

Add documentation for #11806.

### Type of change

- [x] Documentation Update

sandbox/README.md

@@ -24,7 +24,7 @@ A secure, pluggable code execution backend for RAGFlow and beyond.
 
 - Linux distro compatible with gVisor
 - [gVisor](https://gvisor.dev/docs/user_guide/install/)
-- Docker >= `24.0.0`
+- Docker >= `25.0` (API 1.44+) — executor manager now bundles Docker CLI `29.1.0` to match newer daemons.
 - Docker Compose >= `v2.26.1` like [RAGFlow](https://github.com/infiniflow/ragflow)
 - [uv](https://docs.astral.sh/uv/) as package and project manager
 
@@ -34,6 +34,10 @@ A secure, pluggable code execution backend for RAGFlow and beyond.
 
 ---
 
+> ⚠️ **New Docker CLI requirement**
+>
+> If you see `client version 1.43 is too old. Minimum supported API version is 1.44`, pull the latest `infiniflow/sandbox-executor-manager:latest` (rebuilt with Docker CLI `29.1.0`) or rebuild `./sandbox/executor_manager` locally. Older images shipped Docker 24.x, which cannot talk to newer Docker daemons.
+
 ### 🐳 Build Docker Base Images
 
 We use isolated base images for secure containerized execution:
@@ -292,6 +296,22 @@ Follow this checklist to troubleshoot:
   127.0.0.1 es01 infinity mysql minio redis sandbox-executor-manager
   ```
 
+- [ ] **Are you running the latest executor manager image?**
+
+  **Common error:**
+
+  `docker: Error response from daemon: client version 1.43 is too old. Minimum supported API version is 1.44`
+
+  **Fix:**
+
+  Pull the refreshed image that bundles Docker CLI `29.1.0`, or rebuild locally:
+
+  ```bash
+  docker pull infiniflow/sandbox-executor-manager:latest
+  # or
+  docker build -t sandbox-executor-manager:latest ./sandbox/executor_manager
+  ```
+
 - [ ] **Have you enabled sandbox-related configurations in RAGFlow?**
 
   Double-check that all sandbox settings are correctly enabled in your RAGFlow configuration.