add cascadia code nerd font to get working waybar icons

configuration.nix

@@ -40,6 +40,19 @@
   #   useXkbConfig = true; # use xkb.options in tty.
   # };
 
+  # https://nixos.wiki/wiki/Fonts fonts with icons
+  fonts.packages = with pkgs;
+    [
+      (nerdfonts.override {fonts = ["JetBrainsMono" "CascadiaCode" "FiraCode"];})
+    ];
+  fonts.fontconfig = {
+    defaultFonts = {
+      monospace = ["CaskaydiaCove Nerd Font Mono"];
+      sansSerif = ["CascadiaCode Nerd Font"];
+      serif = ["CascadiaCode Nerd Font"];
+    };
+  };
+
   # Enable the X11 windowing system.
   services.xserver.enable = true;