README.md in rating-chgk-v2-1.5.0 vs README.md in rating-chgk-v2-1.6.0

- old
+ new
@@ -2,9 +2,10 @@
 
 ![Gem](https://img.shields.io/gem/v/rating-chgk-v2)
 ![CI](https://github.com/bodrovis/rating-chgk-v2/actions/workflows/ci.yml/badge.svg)
 [![Coverage Status](https://coveralls.io/repos/github/bodrovis/rating-chgk-v2/badge.svg?branch=master)](https://coveralls.io/github/bodrovis/rating-chgk-v2?branch=master)
 ![Downloads total](https://img.shields.io/gem/dt/rating-chgk-v2)
+[![Maintainability](https://api.codeclimate.com/v1/badges/7f66becb60a968a1ca9f/maintainability)](https://codeclimate.com/github/bodrovis/rating-chgk-v2/maintainability)
 
 Ruby client for [competitive "What? Where? When?" (aka "CHGK") API](http://api.rating.chgk.net/). This gem is a replacement for [ChgkRating](https://github.com/bodrovis/ChgkRating) which worked only with the deprecated API version.
 
 ## Installation and requirements
 