Editorial Changes

[Steph]

I've just recieved an email from Amazon to say that my copy of this book is now out of date and that I can download an updated version.

This is apparently because, quote from email

This book has undergone significant changes, so any bookmarks, notes, or highlights you've made will not transfer over to the new version of the book.
The updated version contains the following changes:

Significant editorial changes have been made.

I've never heard of this happening before, can anyone give any idea as to why this would have happened and what the changes are likely to be?