nixos/containerd: StartLimit* options must be in the unit-section

also, raise limits to ensure reasonable startup time, now that StartLimits are actually enforced

nixos/modules/virtualisation/containerd.nix

@@ -44,9 +44,7 @@ in
         KillMode = "process";
         Type = "notify";
         Restart = "always";
-        RestartSec = "5";
-        StartLimitBurst = "8";
-        StartLimitIntervalSec = "120s";
+        RestartSec = "10";
 
         # "limits" defined below are adopted from upstream: https://github.com/containerd/containerd/blob/master/containerd.service
         LimitNPROC = "infinity";
@@ -58,6 +56,10 @@ in
         StateDirectory = "containerd";
         RuntimeDirectory = "containerd";
       };
+      unitConfig = {
+        StartLimitBurst = "16";
+        StartLimitIntervalSec = "120s";
+      };
     };
   };
 }