[DNS Firewall] Call out new IPs if deleting and recreating cluster (#19050)

* [DNS] Update setup.mdx

* Apply suggestion from code review

---------

Co-authored-by: Rebecca Tamachiro <[email protected]>

Author: ngayerie

src/content/docs/dns/dns-firewall/setup.mdx

@@ -41,6 +41,8 @@ Prior to setting up DNS Firewall, you need:
 
 If you forget to save your new IP addresses, find your cluster and click **IP Addresses**.
 
+If you delete your cluster, the assigned set of IPs will be lost. If you recreate the cluster you will get a different set of IPs.
+
 :::
 
 </TabItem> <TabItem label="API">