spring-petclinic/_includes/badges.html

{% if page.badges.twitter %}
<div class="project-sub-link">
    <a href="https://twitter.com/{{ page.badges.twitter }}">
        <div class="spring-icon project-badges twitter" title="Twitter">
        </div>
    </a>
</div>
{% endif %}
{% for badge in page.badges.custom %}
<div class="project-sub-link">
    <a href="{{ badge.url }}">
        <div class="spring-icon project-badges {{ badge.icon }}" title="{{ badge.name }}">
        </div>
    </a>
</div>
{% endfor %}