7.3: Exercise - Add a sentence or two for context on the exercise

[signekb]

Description

There seemed to be some confusion around this exercise - that it's not like the prior exercises in the way that we do exactly what was done together in the code along and then repeating it in the exercise. In this exercise, we go "one abstraction level up" to create a single function to import all files for one kind of data.

I think we need to add a couple of sentences explicitly stating this at the beginning of the exercise to help with that confusion.