How to add custom menus/sections to dashboard?

rails g camaleon_cms:gem_plugin sample_menus

// my_plugin/config/camaleon_plugin.json
"admin_before_load": [
  "my_plugin_admin_before_load"
]

# my_plugin/app/helpers/plugins/sample_menu/main_helper.rb
def my_plugin_admin_before_load
  # add menus
  sub_items1 = [
      {icon: "list", title: 'List of my items', url: '#url_path_here'},
      {icon: "plus", title: 'New My item', url: '#url_path_to_new_here'}
  ]

  # add menus after certain menu
  admin_menu_insert_menu_after("content", "my_plugin_menu", {icon: 'briefcase', title: 'My Menu Group', url: "", items: sub_items1})
  
  # just add a new single menu before created menu 
  admin_menu_insert_menu_before("my_plugin_menu", "single_test_menu2", {icon: 'circle', title: 'Menu before my plugin', url: "#here_single_menu_url"})

  admin_menu_add_menu('custom_last_menu', {icon: 'circle', title: 'This is the last menu', url: admin_plugins_sample_menu_index_path})
end

class Plugins::SampleMenu::AdminController < CamaleonCms::Apps::PluginsAdminController