Some items appear to be miscategorized

[Karin Dalziel]

For instance, this item is a "image"

https://cdrhdev1.unl.edu/family_letters/en/item/shan.D087

Maybe this is correct, but the "image" category has quite a few items that look like documents. Perhaps we need another category of items?

[Karin Dalziel]

To fix this let's not show "category" and change "subcategory" to say category