Rebrand app to KarlDNS

.env.example

@@ -1,10 +1,10 @@
 DDNS_ADMIN_PASSWORD=change-me-long-random-admin-password
-DDNS_PUBLIC_BASE_URL=https://ddns.example.net
-DDNS_HOSTNAME_SUFFIX=ddns.example.net
+DDNS_PUBLIC_BASE_URL=https://karldns.de
+DDNS_HOSTNAME_SUFFIX=karldns.de
 DDNS_DATABASE=/data/ddns.sqlite3
-DDNS_TRUSTED_HOSTS=ddns.example.net
+DDNS_TRUSTED_HOSTS=karldns.de
 DDNS_DNS_PROVIDER=cloudflare
-DDNS_DNS_ZONES=ddns.example.net
+DDNS_DNS_ZONES=karldns.de
 DDNS_REQUIRE_DNS_PROVIDER=1
 DDNS_CLOUDFLARE_API_TOKEN=change-me-cloudflare-token
 DDNS_CLOUDFLARE_ZONE_ID=change-me-cloudflare-zone-id