Documentation-writing is not a goal in itself. Code, tests, documentation – all of these are tools to communicate in writing with other programmers. That includes your future selves as it includes teammates and project collaborators. Kent Beck, “The Documentation Tradeoff”:
I am working on code that reads Apple Reminders data. To fetch reminders from an EKEventStore in EventKit, you need to request permissions. But you can only request permissions for calendar, event, or reminders access if your app’s Info.plist contains the appropriate key.
Nat Pryce released Code Guide, a tool to create interactive code documentation. See his blog post announcement. It’s written in Python and works for Python and Java code. But since Python and Ruby comments look the same, parsing Ruby code works, too.