Missing changes required within main.brs AND emphasis would be nice

[grasponcrypto]

1. There are some necessary changes from lesson 2 to lesson 3 in main.brs which appears to be missing in the lesson. Took a bit to figure out for a newbie:

		msg = wait(0, m.port)
		msgType = type(msg)
		if msgType = "roSGScreenEvent"
			if msg.isScreenClosed() then return
		end if

2. Emphasis on a minor change which is easy to over look in lesson 3:
   <ContentNode title = "DRAMA"/>
<category_node title = "HORROR" feed_url="..."/>
   I think an emphasis should be placed on the fact that ContentNode is modified to category_node as this is a minor difference that is not immediately obvious and if users are manually modifying as i did, as opposed to copy and paste, then it can be quite an annoying learning lesson.

[grasponcrypto]

i placed a pull request for this. feel free to fix phrasing if i used incorrect terminology

[learnroku]

I merged your PR, thanks for helping out!