Add notice about primary_key_type in ActiveStorage migration guide

Author: risinglf

guides/source/active_storage_overview.md

@@ -62,7 +62,7 @@ tables. Use `bin/rails db:migrate` to run the migration.
 
 WARNING: `active_storage_attachments` is a polymorphic join table that stores your model's class name. If your model's class name changes, you will need to run a migration on this table to update the underlying `record_type` to your model's new class name.
 
-WARNING: If you are using UUIDs instead of integers as the primary key on your models you will need to change the column type of `active_storage_attachments.record_id` and `active_storage_variant_records.id` in the generated migration accordingly.
+WARNING: If you are using UUIDs instead of integers as the primary key on your models you will need to change the column type of `active_storage_attachments.record_id` and `active_storage_variant_records.id` in the generated migration accordingly. This can be skipped if you set `Rails.application.config.generators { |g| g.orm :active_record, primary_key_type: :uuid }` in a config file.
 
 Declare Active Storage services in `config/storage.yml`. For each service your
 application uses, provide a name and the requisite configuration. The example