Update system.lua

Added comment so somebody with enough skills could take a closer look.

Last time I made a pull request and didn't fix all the bugs there properly because I wanted somebody else to take a look.
Well, I have fixed the other "exp bugs" there now, so you might as well merge this if you don't have time to figure it out how it should would work with tables.
//After this commit players can't abuse the reward chest if they don't have cap or room in backpacks.
Anyway line 121-124~
	else
		result = "You have found " .. result .. "."
		setPlayerStorageValue(cid, storage, 1)
	end

I think that it would be better to add "exp storage ID" there too and make tables for experience rewards.

I am not very good with tables, therefore I won't even give it a try since I can't figure out how it should work.