Add note to PRA instructions in building.md
Add note to PRA instructions in building.md
shads196770/libvideo,nguyenkien/libvideo,jamesqo/libvideo,i3arnon/libvideo,James-Ko/libvideo,James-Ko/libvideo,nguyenkien/libvideo,shads196770/libvideo,PFCKrutonium/libvideo,jamesqo/libvideo,PFCKrutonium/libvideo