remove ONS links as they no longer work

Author: drkane

findthatpostcode/templates/area.html.j2

@@ -94,8 +94,6 @@
 
     {% call info_block("External links") %}
     <ul class="list pa0 ma0">
-      <li><a href="http://statistics.data.gov.uk/doc/statistical-geography/{{ result.id }}">ONS Geography Linked
-          data</a></li>
       <li><a href="https://mapit.mysociety.org/area/{{ result.id }}.html">MapIt (mySociety)</a></li>
     </ul>
     {% endcall %}