give some love to the waiter app

app/controllers/waiter/product_categories_controller.rb

@@ -0,0 +1,8 @@
+class Waiter::ProductCategoriesController < Waiter::ApplicationController
+
+  def index
+    records = current_supplier.product_categories.include_relation(product: :product_variants)
+    render json: records, each_serializer: Waiter::ProductCategorySerializer, include: %w[products]
+  end
+
+end