Fixed incorrect cc.req.CompleteContract.cooldown in localization

[IO5]

cc.req.CompleteContract.cooldown aka "Must have completed contract <<1>> within the last <<2>>" is produced from .cfg like so:

REQUIREMENT
{
	type = CompleteContract

	contractType = someContract
	cooldownDuration = 23
}

"cooldown" is pretty much the opposite of "within the last". The actual logic in the plugin is a cooldown. Curiously the negative (#cc.req.CompleteContract.cooldown.x) is correct.