nixos: services: transmission: use high file limit

Seeding a lot of files means keeping them all open.

The actual limit was cargo-culted from an open issue.

modules/nixos/services/transmission/default.nix

@@ -71,10 +71,12 @@ in
       };
     };
 
-    # Transmission wants to eat *all* my RAM if left to its own devices
     systemd.services.transmission = {
       serviceConfig = {
+        # Transmission wants to eat *all* my RAM if left to its own devices
         MemoryMax = "33%";
+        # Avoid errors due to high number of open files.
+        LimitNOFILE = 1048576;
       };
     };