### What this PR does / why we need it?
Add quickstart doctest CI
### Does this PR introduce _any_ user-facing change?
no
### How was this patch tested?
- CI passed
- Run `/vllm-ascend/tests/e2e/run_doctests.sh`
Related: https://github.com/vllm-project/vllm-ascend/issues/725
Signed-off-by: Yikun Jiang <yikunkero@gmail.com>
