update README.md

README.md

@@ -255,7 +255,15 @@ end
 
 ## Supported Ruby Versions
 
-This library supports and is tested against the versions listed in `.travis.yml` with [Travis CI build results](https://travis-ci.org/grokify/ringcentral-sdk-ruby).
+This library supports and is [tested against](https://travis-ci.org/grokify/ringcentral-sdk-ruby) the following Ruby implementations:
+
+1. Ruby 2.3.0
+2. Ruby 2.2.0
+3. Ruby 2.1.0
+4. Ruby 2.0.0
+5. Ruby 1.9.3
+6. [JRuby](http://jruby.org/)
+7. [Rubinius](http://rubinius.com/)
 
 Note: Ruby 1.8.7 works except for subscription support which relies on the `pubnub` gem. If there is a need for 1.8.7 support, consider creating a GitHub issue so we can evalute creating a separate library for subscription handling.