README.md in trix-rails-2.1.0 vs README.md in trix-rails-2.2.0

@@ -4,10 +4,12 @@
 
 Want to include Basecamp's awesome [Trix WYSIWYG
 editor](http://trix-editor.org) in your Ruby on Rails application?
 You've come to the right place!
 
-Compatible with Rails 4.2 and up.
+Compatible with Rails 5.0 and up.
+
+_Note: trix-rails 2.x is technically compatible with Rails 4.2 and up, but is no longer tested or maintained. Support for < Rails 5.0 will be dropped in trix-rails 3.x_
 
 # Installation
 
 Add `trix-rails` to your `Gemfile`: