publish _redirect TXT records for URL records

dnsconfig.js

@@ -137,6 +137,7 @@ for (var subdomain in domains) {
     // Handle URL records
     if (domainData.record.URL) {
         records.push(A(subdomainName, IP("192.0.2.1"), CF_PROXY_ON));
+        records.push(TXT("_redirect." + subdomainName, domainData.record.URL));
     }
 
     // Handle reserved domains