Add the seal post script into nix file itself.

Some comments on how to use Gitea.
Switching mentions of users to alice

server-config/configuration.nix

@@ -52,7 +52,7 @@
       auto-optimise-store = true;
 
       # Required by Cachix to be used as non-root user
-      trusted-users = [ "root" "bill" ];
+      trusted-users = [ "root" "alice" ];
     };
   };