feat: Remove redundant link checker in GitHub configuration

[ADubhlaoich]

Proposed changes

This commit removes the defunct check-broken-links workflow configuration, whose utility (Checking for broken links) was replaced by linkchecker some time ago.

It also removes an outdated .txt file whose only content referenced the redundant action. In the future, detail about how the repository is configured will be available in the /documentation folder.

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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