[Doc] Add qwen3 embedding 8b guide (#1734)

1. Add the tutorials for qwen3-embedding-8b
2. Remove VLLM_USE_V1=1  in docs, it's useless any more from 0.9.2


- vLLM version: v0.9.2
- vLLM main:
5923ab9524

Signed-off-by: wangxiyuan <wangxiyuan1007@gmail.com>

docs/source/tutorials/single_npu_multimodal.md

@@ -29,9 +29,6 @@ docker run --rm \
 Setup environment variables:
 
 ```bash
-# Use vllm v1 engine
-export VLLM_USE_V1=1
-
 # Load model from ModelScope to speed up download
 export VLLM_USE_MODELSCOPE=True
 
@@ -143,7 +140,6 @@ docker run --rm \
 -v /etc/ascend_install.info:/etc/ascend_install.info \
 -v /root/.cache:/root/.cache \
 -p 8000:8000 \
--e VLLM_USE_V1=1 \
 -e VLLM_USE_MODELSCOPE=True \
 -e PYTORCH_NPU_ALLOC_CONF=max_split_size_mb:256 \
 -it $IMAGE \