### What this PR does / why we need it?
modify pcp tutorial doc
Because some optimization points have been submitted as PRs and haven't
been merged yet, I'll update the performance data now and refresh it
again after the PRs are merged.
- vLLM version: release/v0.13.0
- vLLM main:
81786c8774
Signed-off-by: weiguihua2 <weiguihua2@huawei.com>