In theory, if you copy an API, you also copy its semantics. The docs for it are supposed to be interchangeable. Its touchy. For example, wouldn't most people rely and use the Java doc even for Android?
Now obviously, redistributing a copyrighted doc on their own website without permission is something else. Cause I'm guessing docs are copyrightable, but not APIs. The whole thing is getting more interesting to be honest.
I think that is just life in tech now. You put out a 'feature' in your app that is new and cool. Two weeks later the same feature shows up in your competitors app.
In our case, always better to be ahead of the curve. You've got a small team with 20 folks who are putting pressure on the 100 person teams at these giant companies.
The way they did it looks much shadier, but I doubt it's actually illegal. The longer text blocks are all original, even if clearly inspired by smartcars. The descriptions of paramters is mostly copied verbatim, but I have my doubts it's copyrightable, after all there are only so many ways to describe what "access_token" does. The overall structure of the documentation is also clearly copied and is probably protected by copyright, but it's easily changed.