Add concept waiter section

app/serializers/product_category_serializer.rb

@@ -0,0 +1,5 @@
+class ProductCategorySerializer < Qwaiter::Serializer
+  embed :ids, include: true
+  attributes :name
+  has_many :products
+end

app/serializers/product_serializer.rb

@@ -0,0 +1,4 @@
+class ProductSerializer < Qwaiter::Serializer
+  embed :ids, include: true
+  attributes :name, :price
+end