ai: add agents file

[tormath1]

mainly inspired from kubernetes/kubernetes

---

I plan to do the same for the flatcar/Flatcar repository with the following additional section:

## Repository instructions
- This repository does not contain any code, it is only for governance purposes
- This repository must be used only to create issues

[Copilot]

Pull request overview

Adds an AGENTS.md file to document repository-specific collaboration norms, intended to guide reviews and contributions in flatcar/scripts (inspired by kubernetes/kubernetes).

Changes:

• Introduces communication preferences (style/tone, “why” over “what”, actionable errors).
• Introduces contributor guidelines (focus, avoid @mentions, avoid certain commit-message keywords, sign-off expectations).
• Adds a prompt to disclose LLM usage (currently underspecified).

Suppressed comments (2)

AGENTS.md:14

• Grammar + trailing whitespace: "pull requests description" is ungrammatical and the line ends with a trailing space. Use a clear plural form and drop the trailing space.

- Do not put `@mentions` in pull requests description 

AGENTS.md:16

• "Sign-off all commits" is not quite actionable as written (readers may not know the exact git command/flag expected). Consider spelling out the mechanism.

- Sign-off all commits

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Suppressed comments (3)

AGENTS.md:8

• The instruction to “Mention the usage of LLMs” is vague (where, when, and what wording). If this file is meant to be followed by humans/agents, make it actionable so it’s consistently applied.

- If an LLM was used to produce substantial changes, mention it in the PR description.

AGENTS.md:15

• There’s an extra space in the Co-authored-by: guideline, which looks like an accidental typo and makes the rendered text slightly odd.

- Do not add `Co-authored-by:` in commit messages

AGENTS.md:16

• “Sign-off all commits” is ambiguous (some folks interpret it as a review/approval sign-off vs a DCO-style Signed-off-by: trailer). Clarify what form of sign-off is required so contributors can comply consistently.

- Sign-off all commits

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Suppressed comments (3)

AGENTS.md:14

• Grammar: “pull requests description” should be “pull request descriptions”.

- Do not put `@mentions` in pull requests description

AGENTS.md:16

• “Sign-off all commits” is easy to misinterpret; it helps to mention the DCO and the concrete mechanism (git commit -s) so agents consistently produce acceptable commits.

- Sign-off all commits

AGENTS.md:2

• AGENTS.md doesn’t say who the “guidelines” are for (humans vs AI agents). Adding a one-liner up top makes the file self-describing when opened outside the PR context.

This issue also appears in the following locations of the same file:

• line 14
• line 16

# flatcar/scripts repository