README.md in rakuten_web_service-1.12.0 vs README.md in rakuten_web_service-1.13.0

@@ -6,10 +6,12 @@
 [![Code Climate](https://codeclimate.com/github/rakuten-ws/rws-ruby-sdk/badges/gpa.svg)](https://codeclimate.com/github/rakuten-ws/rws-ruby-sdk)
 [![Gitter](https://badges.gitter.im/rakuten-ws/rws-ruby-sdk.svg)](https://gitter.im/rakuten-ws/rws-ruby-sdk?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
 
 This gem provides a client for easily accessing [Rakuten Web Service APIs](https://webservice.rakuten.co.jp/).
 
+日本語のドキュメントは[こちら](http://github.com/rakuten-ws/rws-ruby-sdk/blob/master/README.ja.md)。
+
 ## Table of Contents
 
 * [Prerequisite](#prerequisite)
 * [Installation](#installation)
 * [Usage](#usage)
@@ -28,27 +30,31 @@
   * [Rakuten Travel APIs](#rakuten-travel-apis)
 * [Contributing](#contributing)
 
 ## Prerequisite
 
-* Ruby 2.3 or later
+* Ruby 2.5 or later
 
 ## Installation
 
 Add this line to your application's Gemfile:
 
 ```ruby
-  gem 'rakuten_web_service'
+gem 'rakuten_web_service'
 ```
 
 And then execute:
 
-    bundle
+```sh
+bundle
+```
 
 Or install it yourself as:
 
-    gem install rakuten_web_service
+```sh
+gem install rakuten_web_service
+```
 
 ## Usage
 
 ### Prerequisite: Getting Application ID
 
@@ -141,15 +147,33 @@
 
 ```ruby
   ranking_by_age = RakutenWebService::Ichiba::Item.ranking(age: 30, sex: 1) # returns the TOP 30 items for Male in 30s
   # For attributes other than 'itemName', see: http://webservice.rakuten.co.jp/api/ichibaitemsearch/#outputParameter
   ranking_by_age.each do |ranking|
-    puts ranking['itemName']
+    puts item.name
   end
 
   ranking_by_genre = RakutenWebService::Ichiba::Genre[200162].ranking # the TOP 30 items in "水・ソフトドリンク" genre
   ranking_by_genre.each do |ranking|
-    puts ranking['itemName']
+    puts item.name
+  end
+```
+
+### Recipe
+
+```ruby
+  categories = RakutenWebService::Recipe.small_categories
+
+  # Search all small recipe categories.
+  categories.each do |category|
+    category.name
+  end
+
+  recipes = categories.first.ranking
+
+  # Search category recipes.
+  recipes.each do |recipe|
+    recipe.title
   end
 ```
 
 ## Supported APIs