Update sk.coffee (#4089)
Update sk.coffee (#4089)

Concepts translation
probil/codecombat,jeremiahyan/codecombat,fabichoi/codecombat,codecombat/codecombat,codecombat/codecombat,javatlacati/codecombat,jeremiahyan/codecombat,codecombat/codecombat,javatlacati/codecombat,VilkkuV/codecombat,VilkkuV/codecombat,probil/codecombat,VilkkuV/codecombat,probil/codecombat,javatlacati/codecombat,javatlacati/codecombat,jeremiahyan/codecombat,kidaa/codecombat,icodegame/codecombat,Zerrien/codecombat,fabichoi/codecombat,fabichoi/codecombat,icodegame/codecombat,Zerrien/codecombat,VilkkuV/codecombat,Zerrien/codecombat,Zerrien/codecombat,codecombat/codecombat,fabichoi/codecombat,icodegame/codecombat,icodegame/codecombat,javatlacati/codecombat,codecombat/codecombat,kidaa/codecombat,kidaa/codecombat,kidaa/codecombat,jeremiahyan/codecombat,probil/codecombat