### What this PR does / why we need it?
Add the setting description of cudagraph_capture_sizes, guide users to
avoid the common mistakes frequently made when using the EAGLE overlay
fullgraph.
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
No need for testing
- vLLM version: v0.13.0
- vLLM main:
8be6432bda
---------
Signed-off-by: zhaomingyu <zhaomingyu13@h-partners.com>
Signed-off-by: zhaomingyu13 <zhaomingyu13@h-partners.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>