Split "Curated Items" doc into 2-3 pages

[MoltonMontro]

We can provide so much more information, so that creators don't necessarily need to understand core modding principles like MBs, IDs, exploring game files, etc.

Maybe Introduction to Curated Items -> Creating Skins -> Creating Cosmetics?

Subheadings for each Material name. List some common attachment IDs for Secondary materials, or maybe explain some easy ways to find a legacy ID (e.g., using the Wiki or the "Export Asset IDs" button in-game)?