For example my addition to answer was rejected because "it changes too much". But I really think that this change adds useful info, not offtopic and complements the answer. I don't think it's good to add one more answer half of which is consists of the previous.
Note that it's of course hard to know whether an edit of yours has been rejected or not. I once proposed to have a notification feature implemented, but Stack Exchange rejected that proposal.
I'd say your edit was fine. It was factual, added something that couldn't stand as an own answer, and – most of all – didn't change the meaning of the post that was edited. The rejection reason says (emphasis mine):
This edit changes too much in the original post; the original meaning or intent of the post would be lost.
This is not the case here. It adds valid details and resources, which is encouraged. An edit would have been "too radical" if it changed a "yes" to a "no", or completely changed the meaning.
Moreover you're the OP of that question, so the threshold is even a little lower here. Maybe the reviewers didn't see that context – partly to blame on the reviewing tools here.