(minor issue) Intro's for lessons with no description

[moT01]

The first challenge there doesn't have a description. So nothing shows in the intro for the summary.

Probably best to either grab that from the test text when there's no description or, preferably, just leave out the summary when the creator hasn't put one in.

What do you think about the summaries @beaucarnes? Better to grab some text from the description area, or just leave them blank?

I suppose another thing could be to put an option in the yaml to use the descriptions as summaries or not.

[ShMcK]

Do you mean use the step description if no level description exists? Can be done.