Encourage use of console.log

[grncdr]

There is an example of using console.log very early on, but it's never mentioned again as the exercises progress. Reading code and visualizing what it does is incredibly difficult for an absolute beginner, so reminding them a few times throughout the materials to use console.log('some message', variable, variable...) should not only make things easier to understand, but gives them a technique they can continue to use.