Support comments for struct properties about thrifty HOT 2 CLOSED

Hi @a8t3r! Thanks for the reminder - I'd completely forgotten that we dont emit property-level kdoc. We did this for Java in 1.0 but demurred on Kotlin. It's been a long time since I looked at that part of the code, but IIRC I had a notion that we'd want to use @property tags in the data class' top-level doc comment. It might be easy to do, or it might be fiddly. Certainly we could just slap the documentation on the property itself and call it a day. (if so, I think we'd need to do that here but am not positive - would need to check kotlinpoet's behavior, it might need to go on the ParameterSpec declared above also/instead)

Agreed that we could gate that behind a compiler flag/plugin DSL function.

Honestly I won't get to this anytime soon, but I'd be thrilled to take a PR.

from thrifty.

Fixed in #524

I'll try to remember to make a point release when I come back from vacation.

from thrifty.