[Doc] Add --shm-size option to Docker command for qwen3 vl 235B (#3519)

### What this PR does / why we need it?
Added shared memory size option to Docker run command.If shm-size is not
specified, docker will use 64MB by default. In this case,
vllm:EngineCore process may coredump if workload is high.
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
Done

Closes: https://github.com/vllm-project/vllm-ascend/issues/3513

- vLLM version: v0.11.0rc3
- vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.0

---------

Signed-off-by: likeful <irayki@gmail.com>
Signed-off-by: leijie2015 <irayki@gmail.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

docs/source/tutorials/multi_node_qwen3vl.md

@@ -37,6 +37,7 @@ docker run --rm \
 --device /dev/davinci_manager \
 --device /dev/devmm_svm \
 --device /dev/hisi_hdc \
+--shm-size 256g \
 -v /usr/local/dcmi:/usr/local/dcmi \
 -v /usr/local/Ascend/driver/tools/hccn_tool:/usr/local/Ascend/driver/tools/hccn_tool \
 -v /usr/local/bin/npu-smi:/usr/local/bin/npu-smi \