chore(article-link): use old naming of css class name

though the new thumbnail--xxx naming is cleaner
but this kind of change should be postponed until a major release

layouts/partials/article-link/_shortcode.html

@@ -82,7 +82,7 @@
 
 <article class="{{ $cardClasses }}">
   {{ with $featuredURL }}
-    <div class="flex-none relative overflow-hidden {{ $imgWrapperClasses }} thumbnail--simple">
+    <div class="flex-none relative overflow-hidden {{ $imgWrapperClasses }} thumbnail">
       <img
         src="{{ . }}"
         alt=""