We do have something called a Documentation node which enables you to display a bit of documentation as a node in a Blueprint graph. It references special files that use our internal documentation source format (a form of Markdown) and are stored in the Engine/Documentation/Shared directory. Ideally, we would make it more flexible to use a rich text block or reference an HTML file in your project or on the internet and use chromium to display it.
Anyway, I like where your heads are at. We see the benefits of something like this too, especially for documenting sample projects we release. I’ll see whether we can get those improvements made sometime soon-ish.