Expand changelog/readme with info about Turbo vs rails-ujs behavior

Explain a bit more about how `data-confirm` and `data-method` need to be
updated to the turbo versions `data-turbo-confirm` and
`data-turbo-method`, respectively. (and depending on its usage.)

[ci skip]

CHANGELOG.md

@@ -19,7 +19,9 @@
     * If you have a custom responder set on your application and expect it to affect Devise as well, you may need to override the Devise responder entirely with `config.responder = MyApplicationResponder`, so that it uses your custom one. The main reason Devise uses a custom responder is to be able to configure the statuses as described above, but you can also change that config on your own responder if you want. Check the `responders` readme for more info on that.
     * If you have created a custom responder and/or failure app just to customize responses for better Hotwire/Turbo integration, they should no longer be necessary.
     * `:turbo_stream` is now treated as a navigational format, so it works like HTML navigation when using Turbo. Note: if you relied on `:turbo_stream` to be treated as a non-navigational format before, you can reconfigure your `navigational_formats` in the Devise initializer file to exclude it.
-    * OmniAuth "Sign in with" links were changed to buttons that generate HTML forms with method=POST, instead of using link + method=POST that required rails/ujs to work. Since rails/ujs is no longer the default for new Rails apps, this allows the OmniAuth buttons to work in any scenario, with or without rails/ujs and/or Turbo. This only affects apps that are using the default `devise/shared/_links.html.erb` partial from Devise with OmniAuth enabled.
+    * OmniAuth "Sign in with" links were changed to buttons that generate HTML forms with method=POST, instead of using link + method=POST that required rails-ujs to work. Since rails-ujs is no longer the default for new Rails apps, this allows the OmniAuth buttons to work in any scenario, with or without rails-ujs and/or Turbo. This only affects apps that are using the default `devise/shared/_links.html.erb` partial from Devise with OmniAuth enabled.
+    * The "Cancel my account" button was changed to include the `data-turbo-confirm` option, so that it works with both rails-ujs and Turbo by default.
+    * Devise does not provide "sign out" links/buttons in its shared views, but if you're using `sign_out_via` with `:delete` (the default), and are using links with `method: :delete`, those need to be updated with `data: { turbo_method: :delete }` instead for Turbo.
     * Check [this upgrade guide](https://github.com/heartcombo/devise/wiki/How-To:-Upgrade-to-Devise-4.9.0-[Hotwire-Turbo-integration]) for more detailed information.
 
 ### 4.8.1 - 2021-12-16

README.md

@@ -497,6 +497,15 @@ end
 
 _Note_: the above statuses configuration may become the default for Devise in a future release.
 
+There are a couple other changes you might need to make in your app to work with Hotwire/Turbo, if you're migrating from rails-ujs:
+
+* The `data-confirm` option that adds a confirmation modal to buttons/forms before submission needs to change to `data-turbo-confirm`, so that Turbo handles those appropriately.
+* The `data-method` option that sets the request method for link submissions needs to change to `data-turbo-method`. This is not necessary for `button_to` or `form`s since Turbo can handle those.
+
+If you're setting up Devise to sign out via `:delete`, and you're using links (instead of buttons wrapped in a form) to sign out with the `method: :delete` option, they will need to be updated as described above. (Devise does not provide sign out links/buttons in its shared views.)
+
+Make sure to inspect your views looking for those, and change appropriately.
+
 ### I18n
 
 Devise uses flash messages with I18n, in conjunction with the flash keys :notice and :alert. To customize your app, you can set up your locale file: