absolute URL for social image
<!-- Social media previews -->
<meta property="og:title" content="The Binder Project">
<meta property="og:description" content="Reproducible, sharable, interactive computing environments.">
- <meta property="og:image" content="{{static_url("images/logo_social.png")}}">
+ <meta property="og:image" content="https://mybinder.org/static/images/logo_social.png">
<meta name="twitter:card" content="summary_large_image">
{% endblock head %}
</head>
