Incorrect github pages example

[maxwondercorn]

I'm not sure where the source for https://freshbooks.github.io/ember-responsive/ is located (it's not the dummy app) but an example needs updated for 3.x. Specifically in the middle of the page:

{{#if media.isDesktop}}
  Desktop view!
{{/if}}

[k-fish]

Thanks! We're planning to switch ember-responsive to https://github.com/ember-learn/ember-cli-addon-docs soon so we'll make sure to update it.