CAPZ should document which versions of Azure APIs are actually in use

[mboersma]

/kind feature

Describe the solution you'd like

I'd like to be able to determine easily which Azure API is being used by the version of CAPZ I'm using. Ideally this would be automated into the release notes, but even manual would be very helpful to users.

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Environment:

• cluster-api-provider-azure version:
• Kubernetes version: (use kubectl version):
• OS (e.g. from /etc/os-release):