systemd-networkd bridge wiki changes

[ImNtReal]

On my system, I also needed a .netdev file for the bridge

[NetDev]
Name=br0
Kind=bridge

And I had to use restart instead of reload, to get systemd-networkd to pickup the new config, as reload wasn't an option.

[Jamesits]

There are some typos on the wiki, now should be fixed. Also reload is now replaced with restart. Much thanks.