feat: Migrate NGINX Ingress Controller documentation into repository

[ADubhlaoich]

Proposed changes

This pull request migrates the NGINX Ingress Controller documentation from the code repository into this documentation-focused repository. It completes a long-term effort to consolidate all documentation in one place, allowing for better quality assurance across the entire website and tooling.

The migration is represented by moving all content files and updating path references to match the new folder structure. Many filename conventions and Hugo shortcodes have also been updated as part of the effort for consistency, and the engineering team has been added to CODEOWNERS to ensure they are tagged for reviews appropriately.

Checklist

Before merging a pull request, run through this checklist and mark each as complete.

• 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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[JTorreG]

As a content review is not required and this is merely to move the files, approving