Custom HTML-based HIT instruction

I put the 'instruction' field in the 'group_context'

I thought for quite a long time where to put it and I really could not find another better solution
I was just worried that json4s wouldn't know how to handle the `Any`, but I guess they either do runtime class introspection or just try to treat things as strings?

Anyways, I totally believe you that it works, just wanted to make sure you checked.