Typo(?) for callbackOnMeleeAttackBonuses in combat.lua

[Lokean]

Not technically a bug, because everything works as intended, but in combat.lua on 452 there's a callback to 'callbackOMeleeAttackBonuses'. It took me ages to notice why my code wasn't firing for 'callbackOnMeleeAttackBonuses'.

Obviously, 'fixing' this might break a lot of people's addons, so this is mostly here to get caught by people searching for the expected callback name, thinking there's a bug.