TutorialURL use

Does somebody know what is the TutorialURL property of the main screen?
I read an article that explained a few words about its use, but I hadn’t understand it at all.

It is used to view a tutorial page while working on the project at the same time. The TutorialURL field can only accept URLs from AppInventor and Makeroid.

I feel this to be impractical, but it is inherited from App Inventor

Thanks, but I don’t understand what kind of tutorial pages it accept. Like “Basic | Explore MIT App Inventor”?