[Nimble] Updated leading comments

Haha, awesome, thanks! :100: 

But shouldn't this be NimbleTests, since it's meant for that target?

By the way, I'm planning on eliminating these headers altogether sometime soon. I've always thought they were kind of silly to put in the source code (who cares when a file was created? And we have Git to tack that, anyway). I usually remove them but forgot with this project. :expressionless: