Adds item description for BELTED, OUTER and FLOATATION

Item description for item layers other than SKINTIGHT, so that you know if that vest will fit your armor set before you craft it and put it on.

Possible improvements:
Adding a description for items that don't have any layer tag.
Rephrasing BELTED description. I tried "Is worn as a belt", but that sounded even clunkier than "is worn in belt layer".
"This gear is generally worn over clothing."