Add the Let's Encrypt hook dir to the config

Only enabled when there is no TLS cert. This is already part of the
certbot nginx vhost

site-cookbooks/kosmos_gitea/templates/default/nginx_conf.erb

@@ -16,6 +16,10 @@ server {
 <% else -%>
   listen 80;
   server_name <%= @server_name %>;
+
+  location /.well-known {
+    root "/var/www/<%= @server_name %>";
+  }
 <% end -%>
 
   location / {