feature, NGINX One: Add release note for certs on CSGs

[mjang]

Proposed changes

Based mostly on https://github.com/nginx/documentation/pull/34/files

Checklist

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• I have read the contributing guidelines
• I have signed the F5 Contributor License Agreement (CLA)
• I have rebased my branch onto main
• I have ensured my PR is targeting the main branch and pulling from my branch from my own fork
• I have ensured that the commit messages adhere to Conventional Commits
• I have ensured that documentation content adheres to the style guide
• If the change involves potentially sensitive changes¹, I have assessed the possible impact
• If applicable, I have added tests that prove my fix is effective or that my feature works
• I have ensured that existing tests pass after adding my changes
• If applicable, I have updated README.md and CHANGELOG.md

Footnotes

1. Potentially sensitive changes include anything involving code, personally identify information (PII), live URLs or significant amounts of new or revised documentation. Please refer to our style guide for guidance about placeholder content. ↩

[github-actions]

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[mjang]

@sylwang I've proposed fixes for 2 of your 3 comments, and responded to the other. Let me know :)

[ADubhlaoich]

LGTM. Miniscule LOGAF on my edit suggestions: also feels weird seeing the product name with an article ("the") beforehand, but that's probably a me thing.

[JTorreG]

Nothing to add to Alan's comments