[qiuethan]

What this changes

Explains native blockers, explicit holds, issue/PR status tracking and complete-scope closing links in the contributor documentation. Replaces the retired workflow reference with the new board runbook.

Why

Part of #340. Companion to #344; merge #344 first so the workflow and runbook links resolve. Hosted automation acceptance stays open in #340.

Zone

docs only.

• docs/ONBOARDING.md: replaces obsolete readiness limitations with the current blockers, hold and closure policy.
• docs/DEVELOPMENT.md: points the contributor PR workflow to the replacement automation and activation instructions.

How to verify

Read the getting-work and PR-workflow sections against #344's runbook. git diff --check passed, and link targets were checked against that companion change. The complete cleanup passed make check; this PR changes only prose.

Checklist

• Branched from staging and targets staging.
• Changed-file rationale and dependency are documented above.
• Documentation reflects the replacement workflow while retaining its activation caveat.
• Service tests, Python formatting and service contribution checklists are not applicable to these prose-only changes.

Deployment notes

Merge after #344. No service deployment settings change.

[angelayzheng]

lgtm!