docs:expand documentation on has_one_attached method.

Accepted PR's suggestions and added the information to has_many_attached method.

Co-authored-by: Salo Charabati <[email protected]>

Author: 2 people

activestorage/lib/active_storage/attached/model.rb

@@ -74,8 +74,10 @@ module Attached::Model
       # The system has been designed to having you go through the ActiveStorage::Attached::One
       # proxy that provides the dynamic proxy to the associations and factory methods, like +attach+.
       #
-      # If the +:dependent+ option isn't set, the attachment will be purged
-      # (i.e. destroyed) whenever the record is destroyed.
+      # The +:dependent+ option defaults to +:purge_later+. This means the attachment will be
+      # purged (i.e. destroyed) in the background whenever the record is destroyed.
+      # If an ActiveJob::Backend queue adapter is not set in the application set it to
+      # +purge+ instead.
       #
       # If you need the attachment to use a service which differs from the globally configured one,
       # pass the +:service+ option. For example:
@@ -172,8 +174,10 @@ def #{name}=(attachable)
       # The system has been designed to having you go through the ActiveStorage::Attached::Many
       # proxy that provides the dynamic proxy to the associations and factory methods, like +#attach+.
       #
-      # If the +:dependent+ option isn't set, all the attachments will be purged
-      # (i.e. destroyed) whenever the record is destroyed.
+      # The +:dependent+ option defaults to +:purge_later+. This means the attachments will be
+      # purged (i.e. destroyed) in the background whenever the record is destroyed.
+      # If an ActiveJob::Backend queue adapter is not set in the application set it to
+      # +purge+ instead.
       #
       # If you need the attachment to use a service which differs from the globally configured one,
       # pass the +:service+ option. For example: