Added warning about issue to netpol logging

Author: dreia2k

docs/advanced.md

@@ -466,3 +466,5 @@ Packets sent to the NFLOG netlink socket can also be read by using command-line
 tcpdump -ni nflog:100
 ```
 While more readily available, tcpdump will not show the name of the network policy that blocked the packet. Use wireshark's tshark command instead to display the full NFLOG packet header, including the `nflog.prefix` field that contains the policy name.
+
+Network Policy logging of dropped packets does not support [policies with an empty `podSelector`](https://github.com/k3s-io/k3s/issues/8008). If you rely on logging dropped packets for diagnostic or audit purposes, ensure that your policies include a pod selector that matches the affected pods.