This specifically applies to Kindle Fire (not sure about other kindles). You can send a Word doc to your kindle, edit/make notes there, then export the notes – it will email a file with your highlights and notes to wherever you like.
I’m using this right now to edit my son’s book (Son #1). Normally I just hand him my kindle for him to access the edits, but soon he’s going off to college (and he’ll be writing more books!) so this comes just in time.