Add ticket button in greeting

Author: splattater

_includes/sections/greeting.html

@@ -8,6 +8,7 @@ <h1>
     </h1>
     <p>
       <a class="btn2" href="{{ cfpResource.render_path | relativize_url  }}" style="color: white; border-color: white">{{ cfpResource | rdf_property: "rdfs:label", site.language }}</a>
+      <a class="btn2" href="https://www.conftool.net/dataweek2025/" style="color: white; border-color: white">{{str_get_a_ticket}}</a>
     </p>
   </div>
   <figure>