docs(sandbox): update /etc/hosts entry to include required services (#9144)

Fixes an issue where running the sandbox (code component) fails due to
unresolved hostnames. Added missing service names (es01, infinity,
mysql, minio, redis) to 127.0.0.1 in the /etc/hosts example.

Reference: https://github.com/infiniflow/ragflow/issues/8226

## What this PR does

Updates the sandbox quickstart documentation to fix a known issue where
the sandbox fails to resolve required service hostnames.

## Why

Following the original instruction leads to a `Failed to resolve 'none'`
error, as discussed in issue #8226. Adding the missing service names to
`127.0.0.1` resolves the problem.

## Related issue

https://github.com/infiniflow/ragflow/issues/8226

## Note

It might be better to add `127.0.0.1 es01 infinity mysql minio redis` to
docs/quickstart.mdx, but since no issues appeared at the time without
adding this line—and the problem occurred while working with the code
component—I added it here.

### Type of change

- [X] Documentation Update

docs/guides/agent/sandbox_quickstart.md

@@ -63,7 +63,7 @@ docker build -t sandbox-executor-manager:latest ./executor_manager
 3. Add the following entry to your /etc/hosts file to resolve the executor manager service:
 
 ```bash
-127.0.0.1 sandbox-executor-manager
+127.0.0.1 es01 infinity mysql minio redis sandbox-executor-manager
 ```
 
 4. Start the RAGFlow service as usual.