### What this PR does / why we need it?
The PR updates the documentation for DeepSeek-V3.1 and DeepSeek-R1 in
the scenario of prefill-decode disaggregation.
Updated some PD separation-related setting parameters and optimal
configurations. This script has been verified.
- vLLM version: release/v0.13.0
- vLLM main:
bc0a5a0c08
Signed-off-by: chenmenglong <chenmenglong1@huawei.com>