### Features

#### Adds support of `SiteNavigationElement` structured data

Cecil is able to generate automatically [metatags](/documentation/configuration#metatags) for you, useful for SEO and [Open Graph](https://ogp.me/), by including a partial template in HTML `<head>`:

```twig
{% include 'partials/metatags.html.twig' %}
```

This template is also able to generate [structured data](https://developers.google.com/search/docs/advanced/structured-data/intro-structured-data) (`WebSite`, `BreadcrumbList` and `NewsArticle`)  by enabling the following option in config:

```yaml
metatags:
  jsonld:
    enabled: true 
```

Now it also support `SiteNavigationElement`, for example:

```json
{
  "@context":"http://schema.org",
  "@type":"ItemList",
  "itemListElement":[
    {
      "@type": "SiteNavigationElement",
      "position": 1,
      "name": "News",
      "description": "News about Cecil.",
      "url":"https://cecil.app/news/"
    },
    {
      "@type": "SiteNavigationElement",
      "position": 2,
      "name": "Docs",
      "description": "Official documentation of Cecil.",
      "url":"https://cecil.app/documentation/"
    },
    {
      "@type": "SiteNavigationElement",
      "position": 3,
      "name": "Download",
      "description": "How to download Cecil.",
      "url":"https://cecil.app/download/"
    }
  ]
}
```

### Misc

- Documentation updated / fixed
