2 years later and this simple addition is still not in the docs. I have wasted 30 minutes of my life trying to figure this out.
Pity, I was going to integrate Windy API into our new application, but considering the lack of interest in just simply making the first step of the docs complete I lack the confidence to continue further with Windy.
Windy seems to be a shiny on the outside but a bit rotten on the inside.