graphical/plasma: add kwallet warning to plasma.startOnFirstTTY

graphical/plasma.nix

@@ -13,7 +13,17 @@ in
   options.nixowos.graphical.${name} = {
     enable = lib.mkEnableOption name;
 
-    startOnFirstTTY = lib.mkEnableOption "${name} auto start from tty1";
+    startOnFirstTTY = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      description = ''
+        Whether to start ${name} automatically from tty1.
+
+        note: this replaces sddm, which also means kwallet will not be unlocked automatically.
+        kwallet is responsible for storing secrets, using your password for encryption.
+        It's used by browsers, NetworkManager, and many more.
+      '';
+    };
   };
 
   config = lib.mkIf cfg.enable {