Added the rest of the configuration. Still some things to add.

modules/misc/update.nix

@@ -0,0 +1,21 @@
+{ config, ... }:
+
+{
+  system.autoUpgrade = {
+    enable = true;
+    allowReboot = false;
+    flake = inputs.self.outPath;
+    flags = [ "--print-build-logs" ];
+    dates = "02:00";
+    randomizedDelaySec = "45min";
+  };
+
+  nix.gc = {
+    automatic = true;
+    dates = "weekly";
+    options = "--delete-older-than 7d";
+  };
+
+  nix.settings.experimental-features = [ "nix-command" "flakes" ];
+  nix.settings.auto-optimise-store = true;
+}