Fix link for showcases

Author: Sönke Joppien

index.html

@@ -131,7 +131,7 @@ <h3 class="alt-h3 mb-3">Open Government</h3>
     </div>
 
     <p class="text-center">
-      <a href="https://github.com/showcases" class="btn btn-outline">See more showcases &rarr;</a>
+      <a href="https://github.com/collections/government" class="btn btn-outline">See more showcases &rarr;</a>
     </p>
 
   </div>