Embedded structs are not marshalled

[Delerme]

Describe the bug
Feel free to file as a feature request if this is intentional behavior.
The standard json marshaller includes embedded structs but the jsonapi marshaller does not.

Expected behavior
Currently embedded structs are not marshalled: https://go.dev/play/p/hLwiUcAHHcF
However the json marshaller does: https://go.dev/play/p/3cBZDtVDyke

[kpurdon]

Thanks @Delerme -- agreed this should work as you described. We'll look into it.