A4: Make less directive

[alexanderkoller]

Let's make sure that students who already know Pytorch and HF don't feel overconstrained by the way the assignment is phrased. Maybe we should say: Here are the pieces your code needs to have; you can figure out how to do it yourself, or if you can't, here's a way to do it.

But we should still expect them to explain their code in a way that makes it easy for the tutors to process.