The process is:
1. Sign in as a registered user
2. Create a new Forum article
3. Under the "Option" item (Upper-right) of the article . . .
4. ... Select "Nominate to Knowledge Base"
I will receive a notification that a Forum article has been nominated for creating a Knowledge Base article.
As this is a new system and a new process I'm not exactly sure what happens when I approve the request. What's supposed to happen is that you should then be able to clean-up the Forum article (in practice a Knowledge Article should be derived from a conversation between users within a Forum article) and when satisfied, submit it for publishing. I will have the request reviewed and then published to the Knowledge Base.
Let's learn this process together! Please keep me posted as to when you do this so I can make sure I do receive a notification, can approve the nomination and can confirm with you what happens on your end.