Use absURL for image in OpenGraph header

Signed-off-by: hossainemruz <hossainemruz@gmail.com>

layouts/partials/opengraph.html

@@ -8,5 +8,5 @@
 <meta property="og:title" content="{{ $title }}"/>
 <meta property="og:type" content="{{ $type }}"/>
 <meta property="og:description" content="{{ $description }}"/>
-<meta property="og:image" content="{{ $image }}">
+<meta property="og:image" content="{{ $image | relURL }}">
 <meta property="og:url" content="{{ $url }}">