Remove the Historic charter link that has 404ed for several months. T…

…he closest we have for the content it might have reached in the path is already linked out of the concluded working groups page. Fixes #2223. Commit ready for merge.

 - Legacy-Id: 13980

ietf/templates/group/active_wgs.html

@@ -18,7 +18,6 @@
       <h1>Active IETF working groups</h1>
 
       <a class="btn btn-default" href="{% url "ietf.group.views.concluded_groups" %}">Concluded WGs</a>
-      <a class="btn btn-default" href="https://www.ietf.org/dyn/wg/charter/history/">Historic charters</a>
       <a class="btn btn-default" href="{% url "ietf.group.views.all_status" %}">Status Reports</a>
       <a class="btn btn-default" href="{% url "ietf.group.views.chair_photos" group_type="wg" %}">Chair Photos</a>