Active Model: Improve CHANGELOG and documentation for `validates_acce…

…ptance_of` [ci skip]

- Improve CHANGELOG entry for #18439.
- The documentation is updated as per changes in PR #18439 to the
  `accept` option.
- The explanation about the virtual attribute is moved at the end so
  that the arity of `accept` option is explained first.
- Added a note that `message` can also be passed to `validates_acceptance_of`.

activemodel/CHANGELOG.md

@@ -123,11 +123,13 @@
 
     *Wojciech Wnętrzak*
 
-*   Change validates_acceptance_of to accept true by default.
+*   Change `validates_acceptance_of` to accept `true` by default besides `'1'`.
 
-    The default for validates_acceptance_of is now "1" and true.
-    In the past, only "1" was the default and you were required to add
-    accept: true.
+    The default for `validates_acceptance_of` is now `'1'` and `true`.
+    In the past, only `"1"` was the default and you were required to pass
+    `accept: true` separately.
+
+    *mokhan*
 
 *   Remove deprecated `ActiveModel::Dirty#reset_#{attribute}` and
     `ActiveModel::Dirty#reset_changes`.

guides/source/active_record_validations.md

@@ -278,12 +278,6 @@ form was submitted. This is typically used when the user needs to agree to your
 application's terms of service, confirm that some text is read, or any similar
 concept.
 
-This validation is very specific to web applications and this
-'acceptance' does not need to be recorded anywhere in your database. If you
-don't have a field for it, the helper will just create a virtual attribute. If
-the field does exist in your database, the `accept` option must be set to
-`true` or else the validation will not run.
-
 ```ruby
 class Person < ApplicationRecord
   validates :terms_of_service, acceptance: true
@@ -292,16 +286,31 @@ end
 
 This check is performed only if `terms_of_service` is not `nil`.
 The default error message for this helper is _"must be accepted"_.
+You can also pass custom message via the `message` option.
 
-It can receive an `:accept` option, which determines the value that will be
-considered acceptance. It defaults to "1" and can be easily changed.
+```ruby
+class Person < ApplicationRecord
+  validates :terms_of_service, acceptance: true, message: 'must be abided'
+end
+```
+
+It can also receive an `:accept` option, which determines the allowed values
+that will be considered as accepted. It defaults to `['1', true]` and can be
+easily changed.
 
 ```ruby
 class Person < ApplicationRecord
   validates :terms_of_service, acceptance: { accept: 'yes' }
+  validates :eula, acceptance: { accept: ['TRUE', 'accepted'] }
 end
 ```
 
+This validation is very specific to web applications and this
+'acceptance' does not need to be recorded anywhere in your database. If you
+don't have a field for it, the helper will just create a virtual attribute. If
+the field does exist in your database, the `accept` option must be set to
+or include `true` or else the validation will not run.
+
 ### `validates_associated`
 
 You should use this helper when your model has associations with other models