Ignore auto-generated AGENTS.md in markdownlint

[Evangelink]

AGENTS.md is generated by gh copilot-curate (added in #8773) and uses underscore emphasis (skill, agent) plus an H2 first heading. Editing it by hand would be lost on the next regeneration, so add it to the ignore list alongside the other auto-managed paths.

Currently blocks the lint check on all open PRs (#8580, #8586, #8819, #8820, #8823, #4268 ...).

cc @Evangelink

/cc microsoft/testfx-collaborators

[Copilot]

Pull request overview

This PR updates the repository’s markdownlint-cli2 configuration to ignore the root AGENTS.md file, which is auto-generated by gh copilot-curate and currently causes markdownlint failures due to its formatting (underscore emphasis and heading structure). This aligns AGENTS.md with other auto-managed/third-party markdown content already excluded from linting.

Changes:

• Add AGENTS.md to .markdownlint-cli2.jsonc ignore patterns.
• Document the reason inline (auto-generated; do not edit by hand).

Show a summary per file

File	Description
.markdownlint-cli2.jsonc	Adds AGENTS.md to the markdownlint ignore list to prevent lint failures on generated content.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 0

[Evangelink]

Review: Ignore auto-generated AGENTS.md in markdownlint

All 21 review dimensions assessed. Only dimension 21 (Configuration Correctness) is applicable here.

Dimension	Result
1. Algorithmic Correctness	N/A
2. Threading & Concurrency	N/A
3. Security & IPC Contract Safety	N/A
4. Public API & Binary Compatibility	N/A
5. Performance & Allocations	N/A
6. Cross-TFM Compatibility	N/A
7. Resource & IDisposable Management	N/A
8–20. (all others)	N/A
21. Configuration Correctness	✅ Clean

Configuration analysis:

• "AGENTS.md" (bare filename) matches only the root-level file, which is the correct scope — gh copilot-curate generates AGENTS.md at the repo root.
• eng/common/AGENTS.md is already covered by the existing "eng/**/*.md" pattern, so there is no gap.
• The pattern is consistent with the existing "SECURITY.md" entry (bare name for root-only files).
• The inline comment accurately describes the reason for the exclusion.

No issues found. The change correctly unblocks the lint check on open PRs.

Generated by Expert Code Review (on open) for issue #8851 · sonnet46 1.5M