NGF: Upgrade NGF from 1.x to 2.x

[salonichf5]

Proposed changes

Write a clear and concise description that helps reviewers understand the purpose and impact of your changes. Use the
following format:

Problem: Users need documentation to upgrade from NGF v1.6.x to v2.0.x

Solution: Adds an upgrade document with instructions to upgrade

Testing: Describe any testing that you did.

Please focus on (optional): If you any specific areas where you would like reviewers to focus their attention or provide
specific feedback, add them here.

If this PR addresses an issue on GitHub, ensure that you link to it here:

Closes #ISSUE

nginx/nginx-gateway-fabric#3241

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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[ADubhlaoich]

Generally LGTM, made some edit suggestions.

I may do a second pass on the document as part of work in the release branch.

[bjee19]

👍

[ADubhlaoich]

LGTM!