Remove poster

docs_overrides/main.html

 <meta property="og:title" content="{% if page.title %}{{ page.title }} - {% endif %}{{ config.site_name }}">
 <meta property="og:description" content="{{ config.site_description }}">
 <meta property="og:url" content="{{ config.site_url }}">
-<meta property="og:image" content="{{ config.site_url }}/img/poster.png">
 <meta property="og:type" content="website">
 <meta property="og:locale" content="en_US">
 <meta property="robots" content="index, follow">