Add examples for 'ip addr add' and mention correspondence to config file,
add examples for enabling masquerading and IP forwarding,
place the non-root config in its own section and highlight the diffs.
Add tiny hint at systemd-networkd.
Change-Id: I02bd9cfa35c7f2fb338d5d92c2e968fe80574a78
* Some people want to manually create/configure their tun devices,
show them how to do this using ip with the correct parameters
* Let's not call the network device 'ggsn' but rather 'apn0', as
the device has a 1:1 correspondence to the APN, not to the GGSN.
Change-Id: I2fef818bfcb8cb521397136539f492922d5f6def
Neels Hofmeyr
Harald Welte