docs: add notes for libvirtd status (blue-build#27)

closes blue-build#14

README.md

@@ -52,12 +52,14 @@ CoreOS expects the user to run services using [podman](https://podman.io). `moby
 
 To maintain this image's suitability as a minimal container host, most add-on services are not auto-enabled.
 
-To activate any of the pre-installed `cockpit`, `docker`, `libvirtd`, `tailscaled` services, etc:
+To activate pre-installed services (`cockpit`, `docker`, `tailscaled` services, etc):
 
 ```bash
 sudo systemctl enable --now SERVICENAME.service
 ```
 
+Note: `libvirtd` is enabled by default, but only starts when triggerd by it's socket (eg, using `virsh` or other clients).
+
 ### Docker/Moby and Podman
 
 NOTE: CoreOS [cautions against](https://docs.fedoraproject.org/en-US/fedora-coreos/faq/#_can_i_run_containers_via_docker_and_podman_at_the_same_time) running podman and docker containers at the same time.  Thus, `docker.socket` is disabled by default to prevent accidental activation of the docker daemon, given podman is the default.