Update RHCOS registry URL

Author: codyhoag

modules/configuring-firewall.adoc

@@ -33,7 +33,7 @@ There are no special configuration considerations for services running on only c
 |443, 80
 |The `https://console.redhat.com/openshift` site uses authentication from `sso.redhat.com`
 
-|`openshift.org`
+|`*.openshiftapps.com`
 |443, 80
 |Provides {op-system-first} images