[Git] Ignore extra.cf file

.gitignore

@@ -6,6 +6,7 @@ data/conf/dovecot/dovecot-master.userdb
 mailcow.conf
 mailcow.conf_backup
 data/conf/nginx/*.active
+data/conf/postfix/extra.cf
 data/conf/postfix/sql
 data/conf/postfix/allow_mailcow_local.regexp
 data/conf/dovecot/sql