Exercise 3 on "Const Generics" wasn't clear (to me)

[Nic McPhee]

When I did Exercise 3 in the "Const Generics" section I totally didn't understand what was expected until I eventually looked at the solutions. In particular I didn't realize that in each case I wanted to enter the largest value that would still pass the checks in each of the three open slots. When I read it I thought I was supposed to find the smallest value that would work (or a single specific value), and was surprised to find that lots of values worked, including values like 0.

Perhaps it would be useful to say a little more about what the goal here is beyond just "Fix the errors in main"? I could draft something in a PR if that would be helpful.

Thanks for the helpful resource!