Repository: modelscope/evalscope
Issue: [BUG] Configuration error in BFCL-v4 documentation example scripts
Root cause: Documentation Deficiency

## Self-Check List

- [x] I have carefully read the [relevant user documentation](https://evalscope.readthedocs.io/en/latest/get_started/parameters.html)
- [x] I have reviewed the [Frequently Asked Questions](https://evalscope.readthedocs.io/en/latest/get_started/faq.html)
- [x] I have searched and reviewed existing issues to confirm this is not a duplicate problem

## Problem Description

The example evaluation script for BFCL-v4 in the documentation contains an incorrect configuration structure. The `subset_list` parameter was incorrectly placed at the top level of `TaskConfig`, when it should be nested inside `dataset_args['bfcl_v4']`.

This causes the example code to fail when users try to run it directly, as the `TaskConfig` does not accept `subset_list` as a direct parameter.

## Changes Made

**Fixed the configuration error in BFCL-v4 documentation example:**

- Moved the `subset_list` parameter from the top level of `TaskConfig` into the `dataset_args['bfcl_v4']` dictionary
- Corrected the parameter nesting structure to align with the actual API specification
- Updated both English documentation (`docs/en/third_party/bfcl_v4.md`) and Chinese documentation (`docs/zh/third_party/bfcl_v4.md`)

### Before (Incorrect):
```python
task_cfg = TaskConfig(
    model='qwen-plus',
    api_url='https://dashscope.aliyuncs.com/compatible-mode/v1',
    api_key=os.getenv('DASHSCOPE_API_KEY'),
    eval_type='openai_api',
    datasets=['bfcl_v4'],
    eval_batch_size=10,
    subset_list=[  # ❌ ERROR: Placed at TaskConfig top level
        'simple_python',
        'simple_java',
        ...
    ],
    dataset_args={
        'bfcl_v4': {
            'extra_params': {...}
        }
    }
)
```

### After (Correct):
```python
task_cfg = TaskConfig(
    model='qwen-plus',
    api_url='https://dashscope.aliyuncs.com/compatible-mode/v1',
    api_key=os.getenv('DASHSCOPE_API_KEY'),
    eval_type='openai_api',
    datasets=['bfcl_v4'],
    eval_batch_size=10,
    dataset_args={
        'bfcl_v4': {
            # ✅ CORRECT: Nested inside dataset_args
            'subset_list': [
                'simple_python',
                'simple_java',
                ...
            ],
            'extra_params': {...}
        }
    }
)
```

## Files Modified

- `docs/en/third_party/bfcl_v4.md` - Fixed English documentation
- `docs/zh/third_party/bfcl_v4.md` - Fixed Chinese documentation

## Impact

This fix ensures that users can successfully run the BFCL-v4 evaluation by following the documentation examples, preventing runtime errors caused by incorrect configuration structure.

## Type of Change

- [x] Documentation fix
- [x] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

## Testing

- [x] Verified the corrected configuration structure matches the actual API requirements
- [x] Checked both English and Chinese documentation for consistency

## Additional Notes

The `subset_list` parameter is a dataset-specific configuration option and should always be placed within the corresponding dataset's configuration in `dataset_args`, not at the top level of `TaskConfig`.