Update README to mention Rails 6.1+ compatibility

README.md

@@ -1,7 +1,7 @@
-# PublicActivity [![Build Status](https://secure.travis-ci.org/chaps-io/public_activity.svg)](http://travis-ci.org/chaps-io/public_activity) [![Code Climate](https://codeclimate.com/github/chaps-io/public_activity.svg)](https://codeclimate.com/github/chaps-io/public_activity) [![Gem Version](https://badge.fury.io/rb/public_activity.svg)](http://badge.fury.io/rb/public_activity)
+# PublicActivity [![Code Climate](https://codeclimate.com/github/chaps-io/public_activity.svg)](https://codeclimate.com/github/chaps-io/public_activity) [![Gem Version](https://badge.fury.io/rb/public_activity.svg)](http://badge.fury.io/rb/public_activity)
 
 `public_activity` provides easy activity tracking for your **ActiveRecord**, **Mongoid 3** and **MongoMapper** models
-in Rails 5.0+. Simply put: it records what has been changed or created and gives you the ability to present those
+in Rails 6.1+. Simply put: it records what has been changed or created and gives you the ability to present those
 recorded activities to users - similarly to how GitHub does it.
 
 ## Rails 7