sum-of-multiples: Removed a duplicated sentence in README

[GoneUp]

Basically what the title says. I stumbled across the duplicated sentence while doing the exercises.

[petertseng]

thank you, this is good (Because the sentence was indeed duplicated).

I need to ask you a favour. I need you to make the same PR to https://github.com/exercism/problem-specifications/blob/master/exercises/sum-of-multiples/description.md . If you do not, then when this track regenerates its README using that file, the change you've made here will get overwritten. We wouldn't want that to happen.

[GoneUp]

Ah, okay. I didn't know that all tracks have (at least partly) the same description. I will do that tomorrow.

[ijanos]

Thank you! I'm closing this one now, if you don't mind.

[petertseng]

OK, it got merged in problem-specifications.

[petertseng]

removing an extra newline too (generator removes it)

[petertseng]

(I need to change "Removed" to "Remove" - commit messages are imperative)

Thanks for your contribution.