nixos: add XDG sounds module

nixos/modules/config/xdg/sounds.nix

@@ -0,0 +1,22 @@
+{ config, lib, ... }:
+
+with lib;
+{
+  options = {
+    xdg.sounds.enable = mkOption {
+      type = types.bool;
+      default = true;
+      description = ''
+        Whether to install files to support the
+        <link xlink:href="https://www.freedesktop.org/wiki/Specifications/sound-theme-spec/">XDG Sound Theme specification</link>.
+      '';
+    };
+  };
+
+  config = mkIf config.xdg.sounds.enable {
+    environment.pathsToLink = [
+      "/share/sounds"
+    ];
+  };
+
+}

nixos/modules/module-list.nix

@@ -12,6 +12,7 @@
   ./config/xdg/menus.nix
   ./config/xdg/mime.nix
   ./config/appstream.nix
+  ./config/xdg/sounds.nix
   ./config/gtk/gtk-icon-cache.nix
   ./config/gnu.nix
   ./config/i18n.nix