add firewall readme

10.MediaFolder/2.Install_FTP_watch_folder/readme.txt

+Firewall
+========
+
+# echo "40110 40210" > /etc/pure-ftpd/conf/PassivePortRange
+
+ferm.conf
+        # FTP upload for MediaFolder
+        saddr $NET_FTP proto tcp dport (ftp 40110:40210) ACCEPT;
+        mod helper helper ftp ACCEPT;
+
+Debugging
+=========
+
+To enable debugging within pure-ftpd, 
+
+echo yes > /etc/pure-ftpd/conf/VerboseLog
+
+logs are visible with
+
+journalctl -f