I just took a quick glance at your link and I don't consider those stories non-fiction either.
As for what I would consider non-fiction for kids, I'll use the example of a book I bought for my nephew. It was a biography of Pele (since my nephew plays soccer). It was written for children and is definitely non-fiction.
Off the top of my head, other ideas might be the story of a lost dog finding its way home or perhaps a bit of history. It's more about the way the story is told, in these cases, that make it for kids. As long as the subject matter is age-appropriate (however you define that), you can have a wide range. Base it in reality and it is non-fiction.