basic example do not works

[francy328]

I follow the followionf tutorial:
https://www.vuemastery.com/courses/intro-to-vue-js/vue-instance/
and copied file from the solution:
https://codepen.io/VueMastery/pen/JpVXXw?editors=1111

but when I open the index.html with chrome I see:

{{ product }}
{{ description }}

instead of :

Socks
A pair of warm fuzzy socks