Has anyone ever done something like this? It would be even better if Tableau could build this into Tableau where each worksheet on a dashboard could be pointed to and explained by clicking a “Show me how to use this dashboard” button.
Sounds like a good idea. As you said, I imagine you'd be able to embed a viz into a page which contains helped "html" elements. But in terms of building this into the API itself, that'd be an idea to submit to our Ideas forum.