The linked page [1] says that Whatsapp does not share contact list with Facebook.
I have a lot of anecdotal evidence which suggests otherwise, where adding new contacts would immediately have them show up in my list of suggested friends on Facebook, even without any mutual friends. My experiences are from >3 years ago, though, after when I stopped using Facebook.
[1] https://faq.whatsapp.com/general/security-and-privacy/answer...