vagrant: Ensure the whats_next message is printed at the end

The tinkerbell.sh script ends up doing some other work after
calling setup.sh and has set -x enabled so the whats_next message
is likely to be missed. So now save it for later reading as the last
thing done.

Signed-off-by: Manuel Mendez <mmendez@equinix.com>

deploy/vagrant/scripts/tinkerbell.sh

@@ -51,6 +51,9 @@ main() (
 
 	secure_certs
 	configure_vagrant_user
+
+	set +x # don't want the stderr output from xtrace messing with the post-setup-message
+	[[ -f /tmp/post-setup-message ]] && cat /tmp/post-setup-message
 )
 
 main