Update readme & doc for the vllm upgrade to v0.6.2 (#12399)

Co-authored-by: ATMxsp01 <shou.xu@intel.com>

docker/llm/serving/xpu/docker/README.md

@@ -123,6 +123,8 @@ To set up model serving using `IPEX-LLM` as backend using FastChat, you can refe
     --model-path /llm/models/Yi-1.5-34B \
     --device xpu \
     --enforce-eager \
+    --disable-async-output-proc \
+    --distributed-executor-backend ray \
     --dtype float16 \
     --load-in-low-bit fp8 \
     --tensor-parallel-size 4 \

docs/mddocs/DockerGuides/vllm_docker_quickstart.md

@@ -852,6 +852,8 @@ We can set up model serving using `IPEX-LLM` as backend using FastChat, the foll
     --model-path /llm/models/Yi-1.5-34B \
     --device xpu \
     --enforce-eager \
+    --disable-async-output-proc \
+    --distributed-executor-backend ray \
     --dtype float16 \
     --load-in-low-bit fp8 \
     --tensor-parallel-size 4 \