[nginx] Update nginx config to listen in ipv6 too (elastic#9720)

Author: mrodm

packages/nginx/_dev/deploy/docker/nginx.conf

@@ -20,6 +20,7 @@ http {
     access_log  /var/log/nginx/access.log main;
 
     server {
+        listen [::]:80;
         listen 80;
         server_name localhost;