Make handling/problem.md more concise.
Make handling/problem.md more concise.

This wording brings it more in line with the style of learnyounode.

geek/makemehapi,tako-black/makemehapi,tako-black/makemehapi,jakepruitt/makemehapi,austinmcorso/makemehapi,austinmcorso/makemehapi,thegoleffect/makemehapi