You are thinking of errata, and most technical books do have it.
I meant a issues web page like bugzilla or github.
Oh that's is so cool !!! I have read a few O'Reilly books how did I never noticed this.
Technical books have long had errata pages, but often with new issues, known errata are usually fixed. And as mighty as their may be, editors can't list errors that haven't yet been identified. To be in errata, it has to be found too late to fix, but not too late to change.
They often do?
What book(s) are you referring to?
Do you mean a kind of introduction-style insert that addresses things a revision would state?
A "Showerthought" is a simple term used to describe the thoughts that pop into your head while you're doing everyday things like taking a shower, driving, or just daydreaming. The best ones are thoughts that many people can relate to and they find something funny or interesting in regular stuff.