[FEAT] Kubernetes ingress docs

[NeonDaniel]

Objective

Add documentation for ingress-nginx Proxy config and routing requirements for MQ.

Initial Implementation Requirements

• Document cases where proxy config is necessary or not
• Add note about MQ requirements with proxy headers

Other Considerations

• Default use proxy?
• Default to not use external MQ connections?

[NeonDaniel]

Also note proxy-body-size config to allow larger email attachments