Providing an additional config example (VLAN atop brigde)
Adding picture for this and the existing example (VLAN atop Eth)
Adding info on name conventions (eth.20 vs vlan10)
[skip ci]
Like the Developer's Guide the User's Guide should be a single file on
top-level (at least for now), where it references certain sections in
other files.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>