ddns-scripts: Add support for the service dtdns.com

Support is added for the service dtdns.com (https://www.dtdns.com)

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>

net/ddns-scripts/files/services

@@ -101,3 +101,5 @@
 # Variomedia AG
 "variomedia.de" 	"http://[USERNAME]:[PASSWORD]@dyndns.variomedia.de/nic/update?hostname=[DOMAIN]&myip=[IP]"
 
+ #DtDNS
+"dtdns.com"	"http://www.dtdns.com/api/autodns.cfm?id=[DOMAIN]&pw=[PASSWORD]&ip=[IP]"