[Info][main] Correct the mistake in information documents (#4157)

### What this PR does / why we need it?
Correct the mistake in information documents

### Does this PR introduce _any_ user-facing change?
no

### How was this patch tested?
ut

- vLLM version: v0.11.0
- vLLM main:
2918c1b49c

---------

Signed-off-by: lilinsiman <lilinsiman@gmail.com>

docs/source/tutorials/single_npu_qwen2.5_vl.md

@@ -47,6 +47,8 @@ Run the following script to execute offline inference on a single NPU:
 pip install qwen_vl_utils --extra-index-url https://download.pytorch.org/whl/cpu/
 ```
 
+Create a python script with the following content:
+
 ```python
 from transformers import AutoProcessor
 from vllm import LLM, SamplingParams