library/library_checkout/views/library_menu.xml

<?xml version="1.0" ?>
<odoo>
    <act_window id="action_library_checkout"
                name="Checkouts"
                res_model="library.checkout"
                view_mode="kanban,tree,form"
    />
    <menuitem id="menu_library_checkout"
              name="Checkout"
              parent="library_app.menu_library"
              action="action_library_checkout"
    />
</odoo>