[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/multi_npu_qwen3_moe.md

@@ -35,9 +35,6 @@ export VLLM_USE_MODELSCOPE=True
 
 # Set `max_split_size_mb` to reduce memory fragmentation and avoid out of memory
 export PYTORCH_NPU_ALLOC_CONF=max_split_size_mb:256
-
-# For vllm-ascend 0.9.2+, the V1 engine is enabled by default and no longer needs to be explicitly specified.
-export VLLM_USE_V1=1
 ```
 
 ### Online Inference on Multi-NPU