Four kinds of change
A correction to the printed book, a new package release, a teaching note, and a new website feature are all useful, but they mean different things. The distinction matters. If a printed equation is wrong, a reader needs a correction. If the browser gets a new laboratory, the 2017 book did not suddenly become wrong.
So this record uses explicit categories. Book errata correct or clarify the published text. Software entries record changes to the companion package. Teaching entries add material for instructors and students. Website entries describe the maintained companion itself.
No second edition is being announced
There is no second edition of CMNA at present. The site is useful on its own as a maintained companion to the existing book. If the accumulated work eventually supports another edition, there will be a much better record of what actually changed than a blank document and several years of memory.