Add note about touch audits to README

README.md

@@ -133,14 +133,14 @@ end
 
 ### Specifying callbacks
 
-By default, a new audit is created for any Create, Update or Destroy action. You can, however, limit the actions audited.
+By default, a new audit is created for any Create, Update, Touch (Rails 6+) or Destroy action. You can, however, limit the actions audited.
 
 ```ruby
 class User < ActiveRecord::Base
   # All fields and actions
   # audited
 
-  # Single field, only audit Update and Destroy (not Create)
+  # Single field, only audit Update and Destroy (not Create or Touch)
   # audited only: :name, on: [:update, :destroy]
 end
 ```