fix author display

shared/templates/styleguide2/includes/atoms/articles/header_author.html

+{% if page.author_page or page.author %}
   <div class="text-grey-185 mb-4 italic">
     Autor: <span rel="author">
       {% if page.author_page %}
@@ -5,8 +6,9 @@
           href="{{ page.author_page.url }}"
           class="underline text-grey-100"
         >{{ page.author_page.get_full_name }}</a>
-    {% else %}
+      {% elif page.author %}
         {{ page.author }}
       {% endif %}
     </span>
   </div>
+{% endif %}
\ No newline at end of file