Custom Enchantments Guide

[Machine-Maker]

A guide to creating and handling custom enchantments, but not using the traditionally hacky way, instead using the PDC and ItemStack lore as a way to handle custom enchants. This is to discourage bad use of the "API". Should probably include a simple way to add the enchantment to the itemstack, probably by listening to the enchant event, and a way to detect the itemstack was used for something.

Was initially part of #107 but was split off to be its own guide.