Add syncthing service

(cherry picked from commit dd5061d73b)

modules/default.nix

@@ -31,6 +31,7 @@ let
     ./services/network-manager-applet.nix
     ./services/random-background.nix
     ./services/redshift.nix
+    ./services/syncthing.nix
     ./services/taffybar.nix
     ./services/tahoe-lafs.nix
     ./services/udiskie.nix

modules/services/syncthing.nix

@@ -0,0 +1,28 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+{
+  options = {
+    services.syncthing = {
+      enable = mkEnableOption "Syncthing";
+    };
+  };
+
+  config = mkIf config.services.syncthing.enable {
+    systemd.user.services.syncthing = {
+        Unit = {
+          Description = "Syncthing";
+          After = [ "network.target" ];
+        };
+
+        Install = {
+          WantedBy = [ "default.target" ];
+        };
+
+        Service = {
+          ExecStart = "${pkgs.syncthing}/bin/syncthing -no-browser";
+        };
+    };
+  };
+}