docs(score-centering): name the router that supports the recipe

[guapisolo]

Summary

Name the router revision score-centering rollouts need and how to check it.

Symptom & Reproduction

• Symptom: After Allow score centering through compatible SGLang routers #3732, examples/infra_features/score_centering/README.md says unfiltered session rollouts above 20 candidates, or filtered rollouts, "need a compatible SGLang router build" and asks users to verify one before launching, without naming a qualifying build.
• Reproduction: Read the router notes at lines 24 and 85 of that file on main (3005bad).

Root Cause

1. examples/infra_features/score_centering/README.md states the router requirement without a revision.
2. sglang_router stays 0.3.2 across sgl-router-for-miles Refactor and extract RolloutHealthMonitor #21, so its version cannot identify a compatible build.

Fix

Replace both router notes with one bullet in "Supported configurations and limits", next to the existing SGLang requirement: the router must include sgl-router-for-miles #21 (df2c790), checked through Git Commit in smg --version-verbose, which raises the chat top_logprobs limit from 20 to 128 and forwards sampling_logprobs_mode.

The guide no longer uses the Miles Docker image as the requirement, because docker/Dockerfile installs router wheels from a mutable radixark/miles-wheels release tag. It also drops the reference to sgl-project/sglang#41373, which is unmerged and does not forward sampling_logprobs_mode. The live-probe paragraph now says it checks unfiltered requests only. Runtime behavior is unchanged.

Verification

• python3 scripts/tools/sync_example_docs.py --check: passed after regenerating the docs page.
• git diff --check: passed.
• cu130-torch213-x86_64 miles-wheels release: sglang_router-source.json records df2c790, and the wheel's extension embeds 0.3.2 with Git commit df2c790 in the build info printed by smg --version-verbose. This is a strings inspection; the Linux wheel was not executed.
• No live router request was run.

Review Focus

• examples/infra_features/score_centering/README.md router bullet: smg --version-verbose prints one short commit, so a later router build shows a different hash and users must confirm it descends from df2c790.

[claude]

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