Merge pull request #33442 from utilum/ast_guide_setup_clarification

AST Guide: install and migrate tasks needed in new app

guides/source/active_storage_overview.md

@@ -36,10 +36,10 @@ files.
 ## Setup
 
 Active Storage uses two tables in your application’s database named
-`active_storage_blobs` and `active_storage_attachments`. After upgrading your
-application to Rails 5.2, run `rails active_storage:install` to generate a
-migration that creates these tables. Use `rails db:migrate` to run the
-migration.
+`active_storage_blobs` and `active_storage_attachments`. After creating a new
+application (or upgrading your application to Rails 5.2), run
+`rails active_storage:install` to generate a migration that creates these
+tables. Use `rails db:migrate` to run the migration.
 
 Declare Active Storage services in `config/storage.yml`. For each service your
 application uses, provide a name and the requisite configuration. The example