added a language description in the html tag and an alt text to an image tag to improve accessibilty
<head>
<meta charset="utf-8">
<title>{% block title %}Binder{% endblock %}</title>
- </head>{% block meta_social %}
+ {% block meta_social %}
{# Social media previews #}
<meta property="og:title" content="The Binder Project">
<meta property="og:image" content="https://mybinder.org/static/images/logo_social.png">
