I wouldn't say there is a "correct" approach. That was my recommendation based on my experience. The crash course does mention behaviors right in the beginning, and the Stencylpedia has the articles on behaviors right after the introduction, so there is that bit of guidance in that direction.
If you just create a new behavior following the steps shown in the video, it's already there, no extra steps needed. You don't have to attach it to "save it", as soon as it is created, or whenever you save the project, your behavior is saved. You can see them under Resources > Behaviors in the dashboard. So in your example, if you created your behavior with that code, it's already there. You need to attach it to an actor to make use of it, but that's about it.
The problem with discord is that, as ongoing conversations pile up, you can't reliably search for stuff in there, but it is easier to ask questions and get answers (and most of the time faster). The forums and the Stencylpedia are better if you need, as you said, a knowledge base, since you can just look for stuff in them. I have links to my resources in the Shared Resources section (this one) of the forums, and there are others who post game journals or even their own resources to the community as well. All that to say both have their uses.