Rewrote message when player specifies a tier number that is invalid when trying /ebc

Changed from "Tier must be greater than five or less than one," which is incorrect to "Valid tier numbers are 1, 2, 3, 4, or 5." I originally tried "Tier must be greater than zero or less than six" or "tier must be between one and five," but neither attempt was very clear. So, as an alternative, I decided to try specifying to the user which tier numbers ARE valid.

Advantage is that it clearly tells the user, "hey, these are the tiers you can do" instead of leaving them to search a github wiki or such.