### What this PR does / why we need it?
Set `ACL_OP_INIT_MODE` env var default to `0`, since vllm-ascend may
have problems in some scenarios when setting it to `1`.
Plus, the guide https://github.com/vllm-project/vllm-ascend/issues/734
has also been updated.
Signed-off-by: shen-shanshan <467638484@qq.com>