add download badge for docker hub
add download badge for docker hub

cglewis/vent,cglewis/vent,Jeff-Wang93/vent,CyberReboot/vent,lilchurro/vent,Jeff-Wang93/vent,lilchurro/vent,lilchurro/vent,Jeff-Wang93/vent,bpagon13/vent,CyberReboot/vent,bpagon13/vent,bpagon13/vent,CyberReboot/vent,cglewis/vent