nixos: services: nginx: use attrset for vhosts

Attribute sets compose better than lists, it was a mistake to use a list
in the first place...

modules/nixos/services/blog/default.nix

@@ -9,7 +9,7 @@ let
     root = "/var/www/${subdomain}";
   };
 
-  hostsInfo = map makeHostInfo [ "cv" "dev" "key" ];
+  hostsInfo = lib.flip lib.genAttrs makeHostInfo [ "cv" "dev" "key" ];
 in
 {
   options.my.services.blog = {