Add copilot-setup-steps.yml for full agentic PR reviews

[AlBurns-MSFT]

Problem

Recent PRs show the warning:

Copilot was unable to run its full agentic suite in this review.

This happens because the repo lacks a .github/copilot-setup-steps.yml file. Without it, Copilot Code Review cannot spin up a runner environment and falls back to limited static diff analysis.

Fix

Add a minimal copilot-setup-steps.yml that checks out the repo. Since this is a docs-only repo (Markdown TSGs), no build tools or dependencies are needed — just a checkout gives Copilot full repo context for agentic reviews (cross-file references, link validation, structural analysis).

References

• Configuring runners for GitHub Copilot code review
• Example of the warning: Clarify TSG applicability for cluster upgrades #287

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds a .github/copilot-setup-steps.yml file intended to enable GitHub Copilot Code Review’s full agentic runner-based analysis by providing minimal environment setup steps.

Changes:

• Introduces a Copilot setup steps configuration file under .github/.
• Adds a single checkout step to provide full repository context to the agentic reviewer.

[AlBurns-MSFT]

Regarding the two review comments:

1. Format concern ("not a GitHub Actions workflow") — This is incorrect. The official GitHub docs confirm that copilot-setup-steps.yml uses the standard workflow format with on:, jobs:, and runs-on:. That's how you specify the runner environment. The warning on this PR is expected — the file only takes effect once merged to the default branch.

2. SHA pinning for actions/checkout — Fair hardening suggestion but low-risk here: this step only runs in the Copilot review sandbox (not CI), and actions/checkout is a first-party GitHub action. Using @v4 is the convention in GitHub's own docs for this file. Happy to pin if reviewers feel strongly.