Update documentation in dns_sdns.sh for clarity

Clarified usage instructions for obtaining wildcard certificates with the s-dns system. Added steps for setting up the dynamic DNS password and configuring the SDNS_ZONE_KEY variable.

dnsapi/dns_sdns.sh

@@ -1,12 +1,19 @@
 #!/usr/bin/env sh
 
-#  Usage to order a * certificate
-#  ./acme.sh --issue -d '*.www.domain.com'  --dns dns_sdns --server letsencrypt --dnssleep 240
+# s-dns is the Domain Name Registration System of Kyberio GmbH, former Hostway Deutschland GmbH
 
-SDNS_API_URL="https://robot.s-dns.de:8488/"
+# Steps to order a * certificate:
+# First log in into the domain robot, enable the dynamic DNS password for your zone and click save.
 
+# Copy the password and set the SDNS_ZONE_KEY variable with
 # export SDNS_ZONE_KEY=your_zone_key
 
+#
+# ./acme.sh --issue -d '*.www.domain.com'  --dns dns_sdns --server letsencrypt --dnssleep 240
+
+SDNS_API_URL="https://robot.s-dns.de:8488/"
+
+
 ########  Public functions #####################
 
 # Adds a txt record with the specified value. Does not remove an existing record