docs: Add note about running preflight-with-rm-svc-v2.yaml
docs: Add note about running preflight-with-rm-svc-v2.yaml

This is needed for users who want to do the v1.5 -> v1.4 -> v1.5
upgrade.

Main reason for requiring this is that in v1.4 we do not maintain
the svc-v2 BPF maps, so they become stale. When doing the service
restoration from legacy to v2, we do not compare endpoint entries
of the maps (neither does `syncLBMapsWithK8s`), so it's better
to remove the v2 maps to force full restoration from the legacy maps.

Signed-off-by: Martynas Pumputis <6b0d31c0d563223024da45691584643ac78c96e8@lambda.lt>

tgraf/cilium,michi-covalent/cilium,tklauser/cilium,tgraf/cilium,tgraf/cilium,tgraf/cilium,cilium/cilium,cilium-team/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium,tgraf/cilium,tklauser/cilium,tgraf/cilium,cilium-team/cilium,cilium/cilium,michi-covalent/cilium,tklauser/cilium,tklauser/cilium,tklauser/cilium,cilium/cilium,michi-covalent/cilium,michi-covalent/cilium