Layout not seem to be working

### Question

I am trying to follow the getting started instructions, for creating a presentation from a md file.
I am using the md example, but it seems that the { "layout" : "columns" } is not working. Do I need to install something else?

### Background Info/Attempts

So, I have installed npm in ubuntu using apt repository
then I have installed spectacle with

sudo npm install spectacle-cli

Finally I tried to serve the md example with:

sudo spectacle -s example.md

It serves it ok, and the presentation shows on localhost:3000 , but the first slide looks strand seem that --- { "layout" : "columns" } was not correctly parced.