httpserver must be called first.

[TylerNodell]

The documentation says to run open index.html and then proceed with the lesson. However, it doesn't tell the user that they need to start an HTTP server first and then open the HTML file. Then the user needs to navigate to the server webpage.

I think that additional instruction is necessary to tell the students to first run httpserver, then to select the created server. Then run open index.html and proceed with the rest of the lesson.