Make it more clear how to use net.<myname>.*

Make it more clear how to use `net.<myname>.*`
With examples for bonds etc.

Ex:
```
net.ib1-io.hostname:  (will derive from expression {node}-ib1-io)
net.ib1-io.interface_names: ibp35s0
net.ib1-io.ipv4_address:  (will derive from expression 10.10.{201+(87+4*n1)/256}.{(87+4*n1)%256}/20)
net.ib1-io.vlan_id: 0x0001
```