The bar at the top of every page — the site title, the navigation entries,
search, the version and locale switchers, and the theme toggle.

## Usage

```vue
<DuxtHeader />
```

## API

No props. Everything comes from the config: `title`, `navigation`, `links`,
`version` and `locales`.

## Notes

An entry with neither `to` nor `children` means "the documentation". The layer's
own "Docs" entry ships without a `to` on purpose: where the documentation lives
depends on the consumer's prefixes, which the layer cannot know. It resolves to
the first section, which is what makes the default navbar work on a versioned
site and on a flat one alike.