Merge pull request 'Add heroic game launcher to gaming' (#6) from feature/heroic-launcher into master

Reviewed-on: #6

systems/modules/gaming.nix

@@ -6,4 +6,8 @@
     steam.remotePlay.openFirewall = true;
     steam.localNetworkGameTransfers.openFirewall = true;
   };
+
+  environment.systemPackages = [
+    pkgs.heroic
+  ];
 }