_includes/post-author.html
<p class="post-byline">
{% if include.context == 'page' and page.authors %}
{% assign authors = page.authors %}
{% elsif include.context == 'post' and post.authors %}
{% assign authors = post.authors | to_yaml %}
{% endif %}
By
{% for author in authors %}
<span itemprop="author" itemscope itemtype="http://schema.org/Person">
{{ author | team_link }}
</span>
{% assign authorCount = authors | size %}
{% if authorCount > 1 %}
{% unless forloop.last %}
<span class="post-author-comma">,</span>
{% endunless %}
{% endif %}
{% endfor %}
</p>