[Bug]: no specification for TOML object model

[ddstreet]

There is no specification defining the TOML object model, only the general, and in some cases insufficiently specific, user and dev documentation on how to use various TOML configuration parameters.

There should be an actual specification for our TOML, and it should be separate from this azldev repo.

[ddstreet]

initial draft specification md files in this branch: https://github.com/ddstreet/azurelinux/tree/specification