Add upower for laptop battery

laptop/config/battery.nix

@@ -0,0 +1,10 @@
+{ ... }:
+{
+  services.upower = {
+    enable = true;
+    
+    usePercentageForPolicy = true;
+    percentageLow = 15;
+    percentageCritical = 5;
+  };  
+}

laptop/config/default.nix

@@ -3,6 +3,7 @@ let hashedPassword = "$6$y3eb1phxFWnParRT$w1LNfxJ2ByHoiBa5ywh4STGuIK/r4Tnyxx2Xe/
 in {
   imports = [
     ./hardware-configuration.nix
+    ./battery.nix
   ];
 
   networking.hostName = "kiana-laptop";