We recently moved our documentation; do you know where you found those 404s? We're also monitoring via Analytics Tools as well, but finding sooner is better :)
Anyways PSCall is good in Orchestration Plans (can be done in a Configuration Plan, under some conditions), and PSEnsure is best for Configuration Plans.
Explaining Ensure vs Execute can be tricky, but I'd recommend checking out our ebook, called Windows-first Guide to Infrastructure as Code and Continuous Configuration Automation :)