Update tutorial-services.adoc

This seems unwise to recommend.

modules/ROOT/pages/tutorial-services.adoc

@@ -11,6 +11,8 @@ In this tutorial, we will run a script on the first boot via a systemd service.
 
 Let's write a small script that uses https://icanhazip.com/[icanhazip.com] to create an issue file to display as a prelogin message on the console and store it in `public-ipv4.sh`.
 
+NOTE: This is only an example and very risky on production systems because you have no control over what https://icanhazip.com/[icanhazip.com] returns, and runs as root on your server.
+
 [source,bash]
 ----
 cat <<'EOF' > public-ipv4.sh