Sets a cooldown. The user can not run the command again, until the 'duration' is up.
duration- The duration of this cooldown. (e.g
errorMessage- The message that is returned when the cooldown duration is still ongoing.
%time%and other related functions can be used here.
%time%returns how much time is left on the cooldown.
$nomention Hi! $cooldown[30s;Please wait %time%, then use that command again!]