How to edit the list of items that the chiseled bookshelf can hold:

1: Go to mcassets.matdoes.dev/versions/22w42a/downloads/client/ and download the client.jar file by clicking the button in the top left

2: Unzip client.jar and go to data\minecraft\datapacks, then take out the "update_1_20" folder

3: open the "update_1_20" folder, and go to data\minecraft\tags\items, then open bookshelf_books.json

4: edit the list to add any items you want to be able to store in a chiseled bookshelf

5: create a new world in snapshot 22w42a and drag the "update_1_20" folder you just edited into the datapack folder, then apply the datapack

6: open the world and enjoy messing around with chiseled bookshelves