Octane - add octane layout to reflect component co-location

In several places throughtout these guides, we show the file paths for components as `components/my-component.js` and `templates/components/my-component.hbs`. These references need to be updated to reflect the new structure where both hbs and js files are in `components`. Since the cli guides are not versioned, we should show both classic and octane layouts.

Here's the page to update: https://cli.emberjs.com/release/advanced-use/project-layouts/

The work on the component generators is part of another separate issue, #134, so just edit the layouts page for this PR.

This work should target `master` and will be merged with 3.14.