fixing API-XML syntax and add some documentation

nsupdate.d/dist.config.sample

@@ -0,0 +1,33 @@
+# nsupdate.config
+# The nsupdate.sh is processing all .config files by looping.
+# If you want to update an IPv4 and an IPv6 record you need two config files.
+
+# Log file name.
+LOG="$0.log"
+
+# From which site should we get your WAN IP?
+# Note that for IPv4 or IPv6 the IP_CHECK_SITE should work
+# e.g. for IPv4 use api.ipify.org and for IPv6 use api6.ipify.org
+IP_CHECK_SITE="https://api.ipify.org/"
+
+# Use drill instead of nslookup for hostname lookup.
+USE_DRILL="NO"
+
+# Use IPv6 connection.
+IPV6="NO"
+
+# Update an MX record.
+MX="NO"
+
+# Suppress all messages.
+SILENT="NO"
+
+# Login credentials for the inwx admin interface
+INWX_USER="USERNAME"
+INWX_PASS="PASSWORD"
+
+# The hostname that you want to update and it's ID from the inwx interface.
+# Note: You can get the specific domain record ID while editing the given nameserver entry by
+#       inspecting the target URL of the save button.
+DOMAIN="DOMAIN"
+INWX_DOMAIN_ID="123456789"