examples: add krops deployment method

examples/krops/deploy.nix

@@ -0,0 +1,20 @@
+let
+  # FIXME:
+  target = "root@HOSTNAME_OR_IP_ADDRESS";
+
+  extraSources = {
+    "hardware-configuration.nix".file = toString ../hardware-configuration.nix;
+  };
+
+  krops = (import <nix-bitcoin> {}).krops;
+in
+krops.pkgs.krops.writeDeploy "deploy" {
+  inherit target;
+
+  source = import ./sources.nix { inherit extraSources krops; };
+
+  # Avoid having to create a sentinel file.
+  # Otherwise /var/src/.populate must be created on the target node to signal krops
+  # that it is allowed to deploy.
+  force = true;
+}