Makes title, description, and keywords populate the right tags
See https://github.com/jekyll/jekyll-seo-tag
An example of this in action:
```
<!-- Begin Jekyll SEO tag v2.0.0 -->
<title>Docker Engine - Docker</title>
<meta property="og:title" content="Docker Engine" />
<meta name="description" content="Engine" />
<meta property="og:description" content="Engine" />
<meta property="og:site_name" content="Docker" />
<script type="application/ld+json">
{
"@context": "http://schema.org",
"@type": "WebPage",
"headline": "Docker Engine",
"description": "Engine",
"url": "/engine/"
}
</script>
<!-- End Jekyll SEO tag -->
```