Update info about importing math.abs

[Tschis]

Update info about importing math.abs

If you strictly follow the tutorial, the current code will not compile. You have to either use it as math.abs or import it to be able to use it directly. Since it doesn't mention the import, it can be confusing for beginners.

[jdesiloniz]

@Tschis Hi Rodolfo, thanks for your contribution.

I'd say the issue isn't really the use of Math.abs, as if you notice, we're already defining an abs function at the beginning of the tutorial. IMHO the issue is that the function we're defining is targetting Ints instead of Doubles. Would it be possible for you to change that function and remove the references to Math so the exercise uses the function in the tutorial? It should work that way.

[Tschis]

@jdesiloniz Thank you for your answer.

I had actually forgotten about this PR and deleted my previous fork.
So I had to create a new PR (#26).

This one can be closed.