fix(guide): ES6 destructuring assignment with the rest operator

[AdrianSkar]

Minor fixes/enhancements.

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• My pull request has a descriptive title (not a vague title like Update index.md)
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• None of my changes are plagiarized from another source without proper attribution.
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[RandellDawson]

@AdrianSkar Your added solution is still missing a key part:

const arr = removeFirstTwo(source);

Technically the first solution shown is also missing this same line and has the const source = [1,2,3,4,5,6,7,8,9,10]; in the wrong location. Would you mind fixing both solutions? That should be good enough to get this merged.

Thanks

[AdrianSkar]

Sure, @RandellDawson, how about now?

[thecodingaviator]

LGTM! 👍

[RandellDawson]

Thank you for your contribution to the page! 👍
We're happy to accept these changes, and look forward to future contributions. 🎉