Add initializer included in acts-as-taggable-on 10.0.0

Similar to what we do with other gems, we add the commented code.

config/initializers/acts_as_taggable_on.rb

@@ -1,3 +1,12 @@
+ActsAsTaggableOn.setup do |config|
+  # This works because the classes where the base class is a concern, Tag and Tagging
+  # are autoloaded, and won't be started until after the initializers run. The value
+  # must be a String, as the Rails Zeitwerk autoloader will not allow models to be
+  # referenced at initialization time.
+  #
+  # config.base_class = "ApplicationRecord"
+end
+
 module ActsAsTaggableOn
   Tagging.class_eval do
     after_create :increment_tag_custom_counter