Update Staging server setup

Staging-server-setup.md

@@ -2,6 +2,24 @@ Currently used compose file: `/root/frappe-compose.yml`
 
 Restart server: `sudo docker compose -f /root/frappe-compose.yml up -d`
 
-Change DNS name:
+#### Change DNS name
 - Change name in `/root/frappe-compose.yml` and restart server
-- Change directory name inside the `frontend` container `sites` folder and default site in `sites/common_site_config.json`
+- Change directory name inside the `frontend` container `sites` folder and default site in `sites/common_site_config.json`
+
+#### IPv6 Support (from https://docs.docker.com/engine/daemon/ipv6/)
+- Edit `/etc/docker/daemon.json` to contain:
+```
+{
+  "ipv6": true,
+  "fixed-cidr-v6": "2001:db8:1::/64"
+}
+```
+- Edit compose file to look something like:
+```
+networks:
+   default:
+     enable_ipv6: true
+     ipam:
+       config:
+         - subnet: 2001:db8::/64
+```