Automagic route creation

[benhylau]

@darkdrgn2k suggested that in https://github.com/benhylau/mesh-workshop/#8-make-wired-ethernet-link-and-assign-route-with-ip we can change:

   ip addr add 192.168.0.1 dev eth0
-> ip addr add 192.168.0.1/24 dev eth0

This way, we route creation is automatic like this:

root@bloor:~# ip addr add 192.168.33.1/24 dev eth0
root@bloor:~# ip route
...
192.168.33.0/24 dev eth0 proto kernel scope link src 192.168.33.1

We can then omit the manual route add and reword that section.

[benhylau]

623274f3f7505146f8c7d9b0a58bb2101fa48aad