Update README

Indeed this should be patched.

Actually I found out that all of a sudden these settings do nothing in my settings.local.php
Does anyone else experience this?

$config['mail_safety.settings']['enabled'] = TRUE;
$config['mail_safety.settings']['send_mail_to_default_mail'] = TRUE;
$config['mail_safety.settings']['default_mail_address'] = 'YOUR_EMAIL@example.com';

Created a patch for updating the readme, please review.
Thank you.

patch #6 working fine for me. changing status to RTBC.