mayushii/tlp: Set conservative charge thresholds

My usage pattern (mostly docked) otherwise leads to the battery
accumulating one or more charge cycles every day which quickly
deteriorates it.

machines/mayushii/hardware-configuration.nix

@@ -41,7 +41,13 @@
   powerManagement = {
     cpuFreqGovernor = "schedutil";
   };
-  services.tlp.enable = true;
+  services.tlp = {
+    enable = true;
+    settings = {
+      START_CHARGE_THRESH_BAT0 = 75;
+      STOP_CHARGE_THRESH_BAT0 = 92;
+    };
+  };
 
   # Most of the time I want to use both screens at the same time and suspend it
   # regularily by closing the lid