Update net-speed.sh
Update net-speed.sh

Added the common prefix `enx` as possible string for interface detection. See https://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/
Gravemind/i3status,i3/i3status,Dettorer/i3status,Dettorer/i3status,Gravemind/i3status,Gravemind/i3status,Gravemind/i3status,Dettorer/i3status,i3/i3status,i3/i3status,Dettorer/i3status,i3/i3status