Indeed, it's there, on the unittest page, and is exactly what I would have hoped for (preview of the generated document, example with embedded unittest in class to showcase a method). I even thought about writing some explanation myself... Good thing that I didn't jump into it straight away, because everything is already there, just not in the place one could expect it to be.
Yes, the explanation fits the DDoc page more, but it may also just be copied there. Reading about it twice won't harm anyone and this feature might even achieve more traction this way.