added impactstory icon

Author: luismmontilla

_includes/author-profile.html

@@ -112,6 +112,9 @@ <h3 class="author__name">{{ author.name }}</h3>
       {% if author.orcid %}
         <li><a href="{{ author.orcid }}"><i class="ai ai-orcid-square ai-fw"></i> ORCID</a></li>
       {% endif %}
+      {% if author.impactstory %}
+        <li><a href="{{ author.impactstory }}"><i class="ai ai-impactstory ai-fw"></i> Impactstory</a></li>
+      {% endif %}
       {% if author.wikipedia %}
         <li><a href="https://en.wikipedia.org/wiki/User:{{ author.wikipedia }}"><i class="fab fa-wikipedia-w" aria-hidden="true"></i> Wikipedia</a></li>
 {% endif %}