MSOCI-2226: Add containers to subdomain list (#475)

base/github/hostnames.tf

@@ -6,6 +6,7 @@ locals {
     "assets.github.${var.dns_info["public"]["zone"]}",
     "avatars.github.${var.dns_info["public"]["zone"]}",
     "codeload.github.${var.dns_info["public"]["zone"]}",
+    "containers.github.${var.dns_info["public"]["zone"]}",
     "gist.github.${var.dns_info["public"]["zone"]}",
     "media.github.${var.dns_info["public"]["zone"]}",
     "pages.github.${var.dns_info["public"]["zone"]}",