Detail network security documentation

https://pedia.altinn.cloud/sec/security-architecture/networkandendpoint/firewall/ (or pages referred to from this page) should be updated with more details on network design and firewall configuration - e.g:
* Zone/segmentation overview
* Network topology
* Network encryption
* Firewall rules (e.g. open ports)
* Management responsibility

See https://learn.microsoft.com/en-us/azure/cloud-adoption-framework/ready/landing-zone/design-area/network-topology-and-connectivity for inspiration.

. Once approved, relevant parts should be migrated from pedia to docs.

Start with the firewall page at pedia.altinn.cloud/sec/security-architecture/networkandendpoint/firewall/ and follow the pages it refers to. Use Microsoft's Azure network topology and connectivity guide for comparison; done means the relevant pages cover segmentation, topology, encryption, firewall rules, and management responsibility, with approved content migrated to the docs.

Written by the indexing model from the issue text.