book.json

{
  "indent": "book_one",
  "resources": {
    "item_icon": "book.png",
    "gui_background": "background.png"
  },
  "dimensions": {
    "width": 126,
    "height": 250,
    "page_x": 5,
    "page_y": 5,
    "page_width": 116,
    "page_height": 240
  }
}

entry.json

{
  "ident": "entry_one",
  "category": "category_one",
  "pages": [
    {
      "type": "MARKDOWN",
      "text": "Yay, this is some text!"
    },
    {
      "type": "FREEFORM",
      "widgets": [
        {
          "type": "TEXT_LABEL",
          "x": "$center_x",
          "y": "$center_y",
          "text": "Yay, it's a label!"
        }  
      ]
    },
    {
      "type": "RECIPE",
      "variables": {
        "item": "minecraft:crafting_table",
        "subtext": "Because you don't know how to craft this"
      }
    }
  ]
}

template.json

{
  "ident": "RECIPE",
  "widgets": [
    {
      "type": "ITEM",
      "x": 5,
      "y": 5,
      "item": "$get_crafting_component($item, 0);"
    },
    {
      "type": "ITEM",
      "x": 15,
      "y": 15,
      "item": "$get_crafting_component($item, 1);"
    }
    ... you get the idea
  ]
}