rotuer-secrets: remove root_password, add wifi ssid and domainName

this is step one towards getting rid of rotuer-secrets completely and
turning rotuer into a "profile" module that can be less hackily
customised for other people's networks

examples/extneder.nix

@@ -131,6 +131,6 @@ in rec {
     dependencies = [services.dhcpc];
   };
 
-  users.root.passwd = lib.mkForce secrets.root_password;
+  users.root.passwd = lib.mkForce secrets.root.passwd;
   defaultProfile.packages = with pkgs; [nftables strace tcpdump swconfig];
 }