pfSense/pfsense 230c180src/etc/inc dyndns.class, src/usr/local/www services_dyndns_edit.php

Fix DigitalOcean DynDNS client

Fixes the check on the return value since it's been updated to use
HTTP/2 syntax. Also adds logic to allow using `@` to denote updating the
root domain A record as well.

(cherry picked from commit 5878d529949aafef165acdce8e7daae234c9d2c4)
DeltaFile
+6-2src/etc/inc/dyndns.class
+3-1src/usr/local/www/services_dyndns_edit.php
+9-32 files

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