Update README

Author: timfjord

README.md

@@ -1,7 +1,7 @@
 # I18n::Backend::ActiveRecord [![Ruby Style Guide](https://img.shields.io/badge/code_style-rubocop-brightgreen.svg)](https://github.com/rubocop/rubocop) [![Tests Status](https://github.com/svenfuchs/i18n-active_record/actions/workflows/test.yml/badge.svg)](https://github.com/svenfuchs/i18n-active_record/actions) [![Linter Status](https://github.com/svenfuchs/i18n-active_record/actions/workflows/linter.yml/badge.svg)](https://github.com/svenfuchs/i18n-active_record/actions)
 
 This repository contains the I18n ActiveRecord backend and support code that has been extracted from the `I18n` gem: http://github.com/svenfuchs/i18n.
-It is fully compatible with Rails 4, 5 and 6.
+It is fully compatible with Rails 4+.
 
 ## Installation