App Service Domain: API not idempotent and missing exmaple on creation

The App Service Domain API is not idempotent in turns that `PUT`/`PATCH` need some fields (e.g. `consent`, `contact`) which are not returned in a later `GET`. Also, I noticed that the contact information filled in Portal doesn't ends up show in the WHOIS database, where it uses some "preset" contact information instead.

Besideds, there is no example on how to create this resource in current spec, which makes it not easy to reason about. For instance, it is confusing what should pass as `consent.agreedBy`.

Start by reviewing the App Service Domain API specification, especially the PUT, PATCH, and GET definitions and the resource-creation examples. Compare the handling of consent and contact fields across operations, then document a complete creation example and clarify the expected consent.agreedBy value; verify the requested behavior against the reported WHOIS outcome.

Written by the indexing model from the issue text.