docs: restrict pull request labels to ownership only (filigran team / community) (#21)

[SamuelHassine]

Summary

Makes the shared label rule unambiguous so it can never be misread (by a human or an automated reviewer):

• A pull request carries exactly one ownership label — filigran team or community — and nothing else.
• Primary type labels (feature / bug / documentation), area/scope labels, and workflow/triage labels are issue-only and must never be added to a PR.
• Exception: dependency-automation labels (dependencies) on Renovate/Dependabot PRs are exempt.

Updated .github/LABELS.md, .github/labels.yml, and the CONTRIBUTING conventions block.

Closes #21

[SamuelHassine]

🤖 [AI-generated]

Hey @SamuelHassine! 👋 I'm Sam, your convention guardian. I've reviewed PR #22 and here's a summary of what I checked and adjusted:

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🏷️ Labels

Action	Label	Reason
✅ Added	filigran team	Per the shared taxonomy, every pull request must carry exactly one ownership label (filigran team / community) and nothing else. As an org member, filigran team is the correct ownership label; the PR had none.

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📋 PR Description Quality

Overall: Good 🎉

Your PR description looks complete and well-structured. Great job! 🎉

It includes a clear Summary, an enumerated description of the change, the list of updated files (.github/LABELS.md, .github/labels.yml, CONTRIBUTING block), and a linked issue (Closes #21). The title is fully Conventional Commits-compliant (docs: + imperative restrict, no trailing period, with the required (#21) issue reference) — no change needed.

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💡 For future PRs, please follow the contribution conventions and the label taxonomy.

Thanks for contributing! 🚀