Update configure-network.sh in quickstart/metal3.adoc to reflect telco-cloud-examples

[ehsjoar]

The script configure-network.sh has been updated in the telco-cloud-examples to work in scenarios where there is no network_data.json file. This needs to be correctly reflected in the documentation as well.

For more details see

./edge-clusters/airgap/eib/network/configure-network.sh
./edge-clusters/dhcp-less/eib/network/configure-network.sh
./edge-clusters/dhcp/eib/network/configure-network.sh
./edge-clusters/aarch64/eib/network/configure-network.sh