Apparently the CS6 8.1.0 update is ONLY for Creative Cloud subscribers and NOT for those who have purchased perpetual licenses to CS6. Sorry.
Adobe has gone back and added a new feature to CS6: The ability to open newer CC, CC 2013, and CC 2014 files without having to resort to exporting as IDML first.
Now, I need to be clear here: This is not all versions of CS6… this only works with CS6 if you have a subscription to Adobe Creative Cloud, and your CS6 was installed via the CC app! I’m sure many CS6 users are going to grumble about this. For the record, I hope that Adobe will, in the future, make this available to all CS6 users, even without the CC subscription. But for now: CC only.
Anyway, the new version of CS6 showed up in the Creative Cloud app today.
I don't have creative cloud and I was offered the update in Application Manager. If you read the comments on that InDesign Secrets page, you'll read that it was also released for everyone else but without the converter. Not sure why they wouldn't offer a downloadable update though.
InDesign CS6 is an old version, far beyond End Of LIfe. It will not get any update anymore.