machines: rename to 'hosts/nixos'

This will be more consistent in the future if I want to introduce darwin
or home-manager configurations.

hosts/nixos/aramis/networking.nix

@@ -0,0 +1,19 @@
+{ ... }:
+{
+  networking = {
+    hostName = "aramis";
+
+    # The global useDHCP flag is deprecated, therefore explicitly set to false here.
+    # Per-interface useDHCP will be mandatory in the future, so this generated config
+    # replicates the default behaviour.
+    useDHCP = false;
+  };
+
+  my.hardware.networking = {
+    # Which interface is used to connect to the internet
+    externalInterface = "enp0s3";
+
+    # Enable WiFi integration
+    wireless.enable = true;
+  };
+}