fix: Kured default options for sentinel path

- path has to point to the host's /var/run mountpoint
  in the container

locals.tf

@@ -621,6 +621,7 @@ installCRDs: true
     "pre-reboot-node-labels" : "kured=rebooting",
     "post-reboot-node-labels" : "kured=done",
     "period" : "5m",
+    "reboot-sentinel" : "/sentinel/reboot-required"
   }, var.kured_options)
 
   k3s_registries_update_script = <<EOF