Move nh config to a module.

modules/home-manager/nh.nix

@@ -0,0 +1,21 @@
+{
+  config,
+  lib,
+  ...
+}: {
+  options = {
+    crony.nh.enable = lib.mkEnableOption "Enable nh and set it up for automatic cleaning.";
+  };
+
+  config = lib.mkIf config.crony.nh.enable {
+    # Install nh
+    programs.nh = {
+      enable = true;
+      flake = "/home/crony/Repos/nixos";
+      clean = {
+        enable = true;
+        extraArgs = "--keep 5 --keep-since 3d";
+      };
+    };
+  };
+}