add caution about missing security groups for ipv6

This MR introduces:

• add caution about missing security groups for ipv6 networks

content/cloud/network/index.md

@@ -240,6 +240,10 @@ Additional floating IP configuration is available in [official CLI documentation
 ### Obtaining IPv6 address
 Public IPv6 addresses are assigned via SLAAC. After assigning an interface in OpenStack to your instance, verify correct [configuration](/cloud/network/#interface-not-working) of your VM. You can assign interface by directly connecting your VM to the network (make sure you setup DNS records if you decide to use only IPv6) upon creation or by assigning secondary interface.
 
+{{< hint danger >}}
+Don't forget to update your [Security Groups](/cloud/network/#security-rules).
+{{< /hint  >}}
+
 {{< expand "Configuration using Horizon GUI" >}}
 Go to **Project &gt; Compute &gt;  Instances**. Click on the menu **Actions** on the instance you wish to change and click on **Attach interface**.