Update readme

README.md

@@ -29,6 +29,14 @@ This plugin works by automatically setting all attachment slugs to an unique id,
 
 You can also mangle any existing attachment slugs so they won't cause any issues in the future.
 
+## Note for WordPress 6.4
+
+WordPress 6.4 includes [a new feature](https://make.wordpress.org/core/2023/10/16/changes-to-attachment-pages/) that allows you to disable attachment pages. However, this feature redirects attachment pages to the file URL instead of returning a 404 error. To completely disable attachment pages, you should use this plugin instead. The WP 6.4 feature also does not fix the issue where attachment pages reserve slugs for pages.
+
+Also, it seems like this feature does not work as intended, because it will disable attachment pages only for users who are logged in. Anonymous users will still be able to access attachment pages. Also, there is not user interface to enable or disable media pages, they are automatically disabled for new sites but remain enabled for existing sites.
+
+Because of these issues, I recommend you to use this plugin instead of the built-in feature. The plugin will be updated in the foreseeable future, at least until attachment pages are completely removed from WordPress core and older WordPress versions are no longer in use.
+
 ## Requirements
 
 * WordPress 5.2 or later