add alt tag to images

about.md

@@ -27,7 +27,7 @@ of their time to software development.
    {% if mod == 0 or forloop.first %}
    {% endif %}
 <div class="dynare_team_column">
-{% if team_member.webpage %}<a href="{{ team_member.webpage }}">{% endif %}<img class="avatar" src="{{ team_member.img }}" />
+{% if team_member.webpage %}<a href="{{ team_member.webpage }}">{% endif %}<img class="avatar" src="{{ team_member.img }}" alt="Photo of {{ team_member.name }}"/>
 <p>{{ team_member.name }}
 <br>{{ team_member.affiliation }}</p>{% if team_member.webpage %}</a>{% endif %}
 </div>