Add simplified architecture diagrams for traffic flow and config changes

[sarthyparty]

Proposed changes

Add simplified architecture diagrams for traffic flow and config changes.

Problem: The current architecture documentation for NGF is written and presented in a way for a new user or developer to be able to understand.

Solution: Adding new diagrams and explanations for how traffic flows and how config changes are applied and the lifecycle of a gateway.

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.

Closes #3545

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

Release notes

If this PR introduces a change that affects users and needs to be mentioned in the release notes,
please add a brief note that summarizes the change.

[nginx-bot]

Hi @sarthyparty!

Thanks for opening this pull request!
Be sure to check out our Contributing Guidelines while you wait for someone on the team to review this.

[github-actions]

✅ All required contributors have signed the F5 CLA for this PR. Thank you!
_{Posted by the CLA Assistant Lite bot.}

[sarthyparty]

I have hereby read the F5 CLA and agree to its terms