Fix Twittercard thumbnail image

layouts/partials/custom_twitter_card.html

@@ -3,7 +3,7 @@
  {{ with .Params.twitterImage }}
  <!-- Twitter summary card with large image must be at least 280x150px -->
    <meta name="twitter:card" content="summary_large_image"/>
    <meta name="twitter:image:src" content="{{ index . 0 | absURL }}"/>
    <meta name="twitter:image:src" content="{{ print $.Permalink . }}"/>
  {{ else }}
    <meta name="twitter:card" content="summary"/>
  {{ end }}