include explanation that new options are optional

Author: henningkerstan

config.dist.php

@@ -30,21 +30,25 @@
 
 // Enter a URL to use to determine the public IPv4 address. It must 
 // only return an IPv4 address in plain text, otherwise the script will fail.
+// [Optional; will be set to default value 'https://api.ipify.org' if missing.]
 define('IPV4_ADDRESS_URL', 'https://api.ipify.org');
 
 // Enter a URL to use as fallback to determine the public IPv4 
 // address. It must only return an IPv4 address in plain text, otherwise the 
 // script will fail.
+// [Optional; will be set to default value 'https://ipv4.seeip.org' if missing.]
 define('IPV4_ADDRESS_URL_FALLBACK', 'https://ipv4.seeip.org');
 
 // Enter a URL to use to determine the public IPv6 address. It must 
 // only return an IPv6 address in plain text, otherwise the script will fail.
+// [Optional; will be set to default value 'https://ipv6.seeip.org' if missing.]
 define('IPV6_ADDRESS_URL', 'https://ipv6.seeip.org');
 
 // Enter a URL to use as fallback to determine the public IPv6 
 // address. It must only return an IPv6 address in plain text, otherwise the 
 // script will fail.
-define('IPV6_ADDRESS_URL_FALLBACK', 'https://v6.ident.me/');
+// [Optional; will be set to default value 'https://v6.ident.me' if missing.]
+define('IPV6_ADDRESS_URL_FALLBACK', 'https://v6.ident.me');
 
 
 // If set to true, the script will check for your public IPv4 address and add it as an A-Record / change an existing A-Record for the host.