Make podman enablement a personal module

Podman needs some configuration, so I'm splitting it out to its own
module

modules/nixos/default.nix

@@ -17,6 +17,7 @@
     ./kde.nix
     ./kiwix-serve.nix
     ./linode.nix
+    ./podman.nix
     ./print.nix
     ./proxy.nix
     ./remote-builder.nix

modules/nixos/podman.nix

@@ -0,0 +1,21 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+let
+  cfg = config.greg.podman;
+in
+{
+  options.greg.podman.enable = lib.mkEnableOption "Enable podman in NixOS with my updates";
+
+  config.virtualisation.podman = lib.mkIf cfg.enable {
+    enable = true;
+    dockerCompat = true;
+    extraPackages = [
+      pkgs.podman-compose
+    ];
+  };
+}