How do people know there's an update?

[podfeet]

Question on Book updates. TTT40 will be recorded in about a week and a half. When that is complete @Helma will publish an update to the book that will propagate to all versions and if someone arrives in Github (or the page I just created that points to the same files), then they will get the updated chapter.

But how does one know that an update exists if they don’t go looking for it? I think the Apple Book might update itself, but the others have no way of phoning home.

I was thinking of adding a link to podfeet.com/tttbook to sign up for a newsletter to let people sign up for a newsletter to be notified. What do you think? Any better ideas?