bootstrap4-theme/templates/includes/aboutme.html

<div id="aboutme">
    {% if AVATAR %}
        <p>
            <img width="100%" class="img-thumbnail" src="{{ SITEURL }}/{{ AVATAR }}"/>
        </p>
    {% endif %}
    {% if ABOUT_ME %}
    <p class="text-center">
      <strong>{{ AUTHOR }}</strong><br/>
        {{ ABOUT_ME }}
    </p>
    {% endif %}
</div>