feat(tazjin/nixos): serve homepage on yggdrasil

First test of running an Yggdrasil service, lets see how that goes!

Change-Id: Iac10b72f7314a45df13ea539c5c1cef6c994154f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12484
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

users/tazjin/nixos/koptevo/default.nix

@@ -98,6 +98,8 @@ in
     openssh.authorizedKeys.keys = depot.users.tazjin.keys.all;
   };
 
+  users.users.nginx.extraGroups = [ "acme" ];
+
   age.secrets =
     let
       secretFile = name: depot.users.tazjin.secrets."${name}.age";