Update Korean

[RoFoU-UU]

All new items require new translations, and all translation errors have been corrected.
Added the autoPlayNextShort item.

[ImprovedTube]

hi and thank you! @RoFoU-UU

Did you come across difficult / impossible decisions? Which ones might still make sense discussing?
( images.google.com and or trends.google.com often might help.
I say all this by default to document and appreciate translators' efforts while fresh and remembered.)

@yheedev @LYHyoung @msc9533

( unfortunately github doesn't show only new / changed lines here yet, but we could set up another way)