We already do that in a pretty granular way, between language, library, compiler, and toolchain features, unless I'm misunderstanding you.
Regardless, I don't think the cost/benefit is right here; the posts and notes are already pretty short, and should only take a few minutes to read, even if you read all of them.
aye - the note is very short, I meant that given an index at the beginning one could have more detailed sections that highlight the changes for each section of the language to help avoid "can't please everyone" at the risk of "pleasing no one".