Update the player vault prefix

Very small detail, but making note of this Many of the chat message prefixes have been changed, but this one still appears to be the "default" one. It was changed on RPG to a different one. See screenshots. Top is RPG, bottom is Factions. (just an example, it doesn't have to be the same as the RPG one) related note, The factions one says to use /pv (which does not currently work). Ideally this would be fixed (it is on RPG) but if not it should be changed to say /vault