feat: set up Secure Your Fleet use case

[mjang]

Proposed changes

Create end-to-end "use-case" documentation for admins / security engineers who want to use NGINX One Console to "Secure your fleet".

Fleets of NGINX deployments frequently include dozens and many more instances. With this use case, an admin/security engineer can set up the NGINX One Console to send them alerts for appropriate issues. Today, those issues include CVEs and other detected security "misconfigurations" identified by NGINX One Console.

This use case goes somewhat beyond NGINX One Console. This PR removes roadblocks to success in the following ways:

• It clarifies what users need to access the NGINX One Console, specifically with:

  • Supporting checks of appropriate licenses
  • Describing the detailed process of setting up a tenant

• It then shows users, step by step, how to set up notifications when one/more of their instances have CVEs and other detected security issues.

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. ↩

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