docs: move n4a load balancer topic

[JTorreG]

Proposed changes

Moves the NGINXaaS for Azure Load balancer topic to the root of the docs.

• Fix link dependencies related to the move

Checklist

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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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