Docs: Add a @since note for the recovery_mode_email filter about the $email argument now including the attachments key.

Follow-up to [48964].

See #51276.

git-svn-id: https://develop.svn.wordpress.org/trunk@48994 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-recovery-mode-email-service.php

@@ -206,6 +206,7 @@ When seeking help with this issue, you may be asked for some of the following in
 		 * Filters the contents of the Recovery Mode email.
 		 *
 		 * @since 5.2.0
+		 * @since 5.6.0 The `$email` argument includes the `attachments` key.
 		 *
 		 * @param array  $email {
 		 *     Used to build a call to wp_mail().