Don't render 'By' if no authors

pelican/themes/simple/templates/index.html

@@ -11,11 +11,13 @@
             <section>{{ article.summary }}</section>
             <footer>
                 <p>Published: <time datetime="{{ article.date.isoformat() }}"> {{ article.locale_date }} </time></p>
+                {%- if article.authors %}
                 <address>By
                     {% for author in article.authors %}
                         <a href="{{ SITEURL }}/{{ author.url }}">{{ author }}</a>
                     {% endfor %}
                 </address>
+                {%- endif %}
             </footer>
         </article>
     {% endfor %}