- explain what happens on gluon-reconfigure
- show workflow to alter the wired network config
- update examples
- update 'has changed in' section

resolves #2474

Co-authored-by: Tom Herbers <mail@tomherbers.de>
Co-authored-by: David Bauer <mail@david-bauer.net>
Co-authored-by: Andreas Ziegler <dev@andreas-ziegler.de>

Co-authored-by: Tom Herbers <mail@tomherbers.de>
Co-authored-by: David Bauer <mail@david-bauer.net>
Co-authored-by: Andreas Ziegler <dev@andreas-ziegler.de>

The 'auto' attribute still allows enabling the interface using ifup, which
is not intended when wired mesh is disabled.

propose to make uci commit more specific to minimize unwanted changes in other temporary written config files like wireless ssid (in some offline changers)

Use the common term; the "Expert Mode" never was a distinct mode of
operation anyways.

Fixes #376