Use exclusive flag for using with chrome/chromium

[tuxflo]

Hi! At first thanks a lot for your script, it is working great on my ubuntu 18.04 System on WebRTC sessions (Jitsi Web conference). Just a small hint for chrome/chromium users to get the v4l2loopback device working one can use the exclusive_caps=1 flag as described here. The entire modprobe section then looks like that:

# echo "Probing v4l2-loopback"
sudo rmmod v4l2loopback 2> /dev/null
sudo modprobe v4l2loopback video_nr=7 'card_label=myFakeCam' exclusive_caps=1

Maybe you can put a hint on that in the Readme.md.