Unable to document @data

[ParadaCarleton]

As in the title, it's not currently possible to document Structs created using the @data macro; adding a docstring above them results in an error. (You can attach the docstring further down, but that makes the code a bit harder to read.)

Relatedly, the current naming of ADTs as x's constructor makes it a bit harder to document them. Could you explain what's going on with them?

[kapple19]

The error that gets reported is '@data' not documentable so do I understand correctly that the data macro needs to recognise and correctly handle when the expression it receives starts with a string?