message: Add rel="nofollow" on Versions links
diff: <li class="pure-menu-item">
  <a
  href="{{ release_url | safe }}"
  + {# We only want crawlers to crawl the /latest/ URLs, not /1.2.3/ URLs. #}
  + rel="nofollow"
  class="pure-menu-link{% if warning %} warn{% endif %}"
  {% if warning %} title="{{ warning }}"{% endif %}
  {% if retain_fragment %}data-fragment="retain"{% endif %}
  