Improve remotes documentation in config

smtprelay.ini

@@ -83,8 +83,19 @@
 ;          E.g. "[email protected],@appsrv.example.com"
 ;allowed_users =
 
-; Relay all mails to this SMTP server.
+; Relay all mails to this SMTP servers.
 ; If not set, mails are discarded.
+;
+; Format:
+;   protocol://[user[:password]@][netloc][:port][/remote_sender][?param1=value1&...]
+;
+;   protocol: smtp (unencrypted), smtps (TLS), starttls (STARTTLS)
+;   user: Username for authentication
+;   password: Password for authentication
+;   remote_sender: Email address to use as FROM
+;   params:
+;     skipVerify: "true" or empty to prevent ssl verification of remote server's certificate
+;     auth: "login" to use LOGIN authentication
 
 ; GMail
 ;remotes = starttls://user:[email protected]:587