In the Documentation Center there is a link on a function's page at the top right hand corner that says "Updated: Show Changes" which you can click on to highlight changes since the previous major release. Also at the bottom left hand corner of the page is further history information. So, yes, I am puzzled about any changes in ActionMenu
for example: I don't know of any and none are listed on the page--last significant change seems to be in Version 8. DynamicModule was updated in version 10 by adding the (very much needed) SaveDefintions
option along with other things.
I am guessing that the final bullet in the list at the link you posted has to do with bug fixes--I agree that it is oddly worded to suggest that there are significant changes in design functionality aside from fixing internal bugs.
All fo the other bullets on that page are worded to indicate that they are bug fixes and modifications to already deployed functionality.
Perhaps a WRI employee can comment.