README.md in japanese_calendar-0.4.0 vs README.md in japanese_calendar-0.4.1

@@ -1,5 +1,5 @@
-# Japanese Calendar [![Gem Version](https://badge.fury.io/rb/japanese_calendar.svg)](https://badge.fury.io/rb/japanese_calendar) [![Build Status](https://travis-ci.org/RyoYamamotoJP/japanese_calendar.svg?branch=master)](https://travis-ci.org/RyoYamamotoJP/japanese_calendar) [![Code Climate](https://codeclimate.com/github/RyoYamamotoJP/japanese_calendar/badges/gpa.svg)](https://codeclimate.com/github/RyoYamamotoJP/japanese_calendar) [![Test Coverage](https://codeclimate.com/github/RyoYamamotoJP/japanese_calendar/badges/coverage.svg)](https://codeclimate.com/github/RyoYamamotoJP/japanese_calendar/coverage)
+# Japanese Calendar [![Gem Version](https://badge.fury.io/rb/japanese_calendar.svg)](https://badge.fury.io/rb/japanese_calendar) [![Build Status](https://travis-ci.org/RyoYamamotoJP/japanese_calendar.svg?branch=master)](https://travis-ci.org/RyoYamamotoJP/japanese_calendar) [![Maintainability](https://api.codeclimate.com/v1/badges/661b3d2765caae7906c6/maintainability)](https://codeclimate.com/github/RyoYamamotoJP/japanese_calendar/maintainability) [![Test Coverage](https://api.codeclimate.com/v1/badges/661b3d2765caae7906c6/test_coverage)](https://codeclimate.com/github/RyoYamamotoJP/japanese_calendar/test_coverage)
 
 Japanese calendar utility for Ruby.
 
 ## Installation