`docs/route.js` Presence Causes API Documentation To Not Be Found/Error

I always use Ember's generators, even when creating my Dummy app's routes. Every time that I spun up `ember-cli-addon-docs` I'd translate the _getting started_ instructions to the `ember generate ...` commands.

This caused me to run an `ember g --dummy route docs` which politely creates my `template.hbs` and `route.js`. What I discovered was that if the `route.js` was present, my API documentation in the sidebar would only show up if I started at the `application-index` route and navigated directly to the docs route.

1. When the `docs` route would refresh, my API doc links in the sidebar would disappear.
1. If I was viewing a specific api-doc page and reloaded it, I'd get the following error: `Error while processing route: docs.api.item Cannot read property 'get' of null TypeError: Cannot read property 'get' of null`.

The fix for this was for me to remove my empty `docs/route.js`.

We might want to mention this in the _getting started_ documentation for `ember-cli-addon-docs` but even more we might want to fix this. I don't feel that the mere presence of an empty `docs/route.js` should somehow impede the `model()` hook from firing.

_I am happy to fork and fix this if someone knows what might be the ailing cause and can point me in the correct direction._ I too am happy to update the getting started section of your docs with this warning message.

Thanks again for this addon.