Update documentation for CERT-EU

[augustincolle-digit]

Update documentation to include CERT-EU's point of view.

[barrjam]

It would be helpful to have a single document that we can distribute as a PDF similar to our azap documentation that is generated from the README azap README.pdf. This is something we can send out by email.

• So I suggest consolidating the information in the Confluence page into the README.md https://webgate.ec.europa.eu/fpfis/wikis/pages/viewpage.action?spaceKey=CVTF&title=Azure+Secure+Landing+Zone
• Replace the confluence pages with a link to the AzLandingZone README.md
• I also suggest including information about development and how to submit changes.
• Going forward document should refer to azap