doc: add upgrade note about nativeRoutingCIDR deprecation
doc: add upgrade note about nativeRoutingCIDR deprecation

Missed by e03bfffd55466366289944dd087b9ae18593355f

Signed-off-by: Alexandre Perrin <60c6d277a8bd81de7fdde19201bf9c58a3df08f4@kaworu.ch>

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