`description` in a trait is not inherited by the resource

With this trait:

```
- legacyPages:
    description: |
      This is a legacy resource, prefer accessing pages from the `/pages` resource.
```

and this resource:

```
/pages:
  is: [legacyPages, subCollection]
```

the description is not inherited, as it's visible in projects that use `raml-js-parser` (for ex. `api-console` and `raml2html`).
