patata-pack2/patchouli_books/patatapack_guide/en_us/entries/test_entry.json

{
    "name": "Test Entry",
    "icon": "minecraft:writable_book",
    "category": "yourbooknamespace:test_category",
    "pages": [
        {
            "type": "patchouli:text",
            "text": "This is a test entry, but it should show up!"
        }
    ]
}