blog: give each post its own closing heading instead of sixteen sections called 'The principle'

src/content/blog/sleep-half-the-fleet.md

@@ -81,7 +81,7 @@ so. The wrong response is to call that a false alarm. It isn't. It's the system
 deliberate act, and the deliberate act is written down where the alert can be checked against it. The
 porter doesn't disable the alarm panel for the dark wings - he checks the panel against the log.
 
-## The principle
+## Design for off
 
 Design for off. A node you can power down without ceremony is a node whose whole truth lives outside it - in documents, in git, in the log, and that is precisely the property you need on the day a node goes down
 without asking. The fleet you can put to sleep on purpose and the fleet that shrugs off losing a node in