Mention partial updates in environment.rb to make it easier for people to opt-in if they know it's safe

railties/environments/environment.rb

@@ -64,4 +64,7 @@ Rails::Initializer.run do |config|
 
   # Activate observers that should always be running
   # config.active_record.observers = :cacher, :garbage_collector
+
+  # Make ActiveRecord only save the attributes that have changed since the record was loaded.
+  # config.active_record.partial_updates = true
 end