docs: Clarify deprecated "prefilter-devices"
docs: Clarify deprecated "prefilter-devices"

Make it clear how users can select devices for the prefiltering.

Reported-by: André Martins <bc9800b9d52a24cce72a73dd528afed53f10e5fc@cilium.io>
Signed-off-by: Martynas Pumputis <6b0d31c0d563223024da45691584643ac78c96e8@lambda.lt>

cilium/cilium,cilium/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium,michi-covalent/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium