Wrap example ADT fields in Column

[raehik]

The Haddocks for module Rel8 describe how you can define sum types with all the relevant Rel8 plumbing, using an example. But the inner types use plain f:

data Thing f = ThingEmployer (Employer f) | ThingPotato (Potato f) | Nullary
    deriving stock Generic

data Employer f = Employer { employerId :: f Int32, employerName :: f Text}
-- ...

instead of Column f which erases the Result ~ Identity wrapper, for ergonomics. Probably it should be using that. (I can't find any other cases in the docs that don't wrap a column in Column.)

Doesn't impact the Haddock example that uses this data type.

[TeofilC]

Good spot!