I think this already exists. If your posts has been edited then you will see a notification to that effect.

![Edit Notification][1]

If you click on the date of the edit then you will be taken to the /revisions page for the post in question in this case https://serverfault.com/posts/347886/revisions which shows additions in green and removals in red.


  [1]: https://i.sstatic.net/FNhVx.png