Update and clarify NGINX One RBAC docs

[tstraley]

Proposed changes

Problem: Inaccuracies and confusing sentences in new RBAC docs for N1.

Solution: Reworded and revised for accuracy.

Testing: N/A

Please focus on (optional): N/A

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. ↩

[ADubhlaoich]

Generally LGTM, two edit suggestions. The suggestion related to the use of inline HTML applies to the whole document, but I only addressed the lines within the scope of the PR.

[mjang]

@tstraley Thanks so much for clarifying! Next time, I'll include you in my list of reviewers. I've added some suggestions mostly to focus on the "second person", to make our recommendations more personal for the reader.