indeed but its super handy ... usually official documentations are no where to be found mostly because documentation ppl are leaving the company or websites/dev portals restructuring and so on ... and learning from blogs of someone is never perfect and leaves a lot to be desired.
I believe it is good if kotlin have such page... and it is better to have it earlier than later because the features are adding and yeah.. it will be harder to track what went where.
Also the versioning wiki page in Java I use often in presentations to hype for the language to see what has been added in an year back in the day, just in an year or how early it was and so on...