In addition to Ollie's answer, I would also like this. As an example, one of my posts which included the word "color" was edited 1 to change the spelling of that one word into "colour". It was only changing one character, and I was notified of it by another user pinging the editor.
I would like to know of edits like these, because they are trivial and I don't like the word "color" to be spelled "colour", at least in my posts.
And sometimes one character can make a difference. For instance, a user with full editing rights could just change the d in duck to an f on a really old post with a lot of answers. Nobody would most likely notice if the author of the post wasn't notified.
Maybe we could have this as a profile setting - so some can opt out of these notifications. I know some people just hate having their inbox full, especially high rep users.
1 - This editor had full editing rights