If we list all the natural numbers up to and including 15 that are
multiples of either 3 or 5, we get 3, 5, 6 and 9, 10, 12, and 15.

The sum of these multiples is 60.

Write a program that can find the sum of the multiples of a given set of
numbers.

If we list all the natural numbers up to but not including 15 that are
multiples of either 3 or 5, we get 3, 5, 6 and 9, 10, and 12.

The sum of these multiples is 45.

Write a program that can find the sum of the multiples of a given set of
numbers.

Correct inconsistency in sum of multiples readme
Correct inconsistency in sum of multiples readme

The exercise states that the multiples should not include the higher bound, but then the
example immediately after that includes the upper bound.

Fixes exercism/exercism.io#2579
