examples, oneshot services rework

Signed-off-by: fbt <fbt@fleshless.org>

examples/services/sshd

@@ -0,0 +1,10 @@
+#!/usr/bin/env ssm
+
+service_respawn = always
+service_command = /usr/bin/sshd -D -f "/etc/ssh/sshd_config"
+
+pre_start() {
+	if ! [[ -e "/etc/ssh/ssh_host_key" ]]; then
+		ssh-keygen -A
+	fi
+}