JS Lesson 3

[taw]

Not a PR as it's some gist code with separate download.

It would be useful to move js from head to end of the body as that's one less thing to explain to the student at this point why something works in console and not inside script.js.

And it's same story for both exercises.

Another story is that teaching people about keyup event which only sort of does the right thing is probably counterproductive nowadays. input event is going to cause a lot fewer issues.