feat: Add F5 WAF NGINX configuration examples

[ADubhlaoich]

Proposed changes

This commit adds two configuration examples for F5 WAF for NGINX, showing exactly where the F5 WAF for NGINX directives could be added to NGINX configuration.

Beyond re-adding examples that existed in a prior state of documentation, line highlighting has been added to draw a reader's attention to the important lines.

Checklist

Before sharing this pull request, I completed the following checklist:

• I read the Contributing guidelines
• My branch adheres to the Git conventions
• My content changes adhere to the F5 NGINX Documentation style guide
• If my changes involve potentially sensitive information¹, I have assessed the possible impact
• I have waited to ensure my changes pass tests, and addressed any discovered issues

Footnotes

1. Potentially sensitive information includes personally identify information (PII), authentication credentials, and live URLs. Refer to the style guide for guidance about placeholder content. ↩

[github-actions]

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