Use vcgencmd within a docker node-red container

@DannyBoyKN
You have different Linux distributions in a host and in a container.
You should build your own image, in your case Dockerfile will looks like:

FROM    ctmagazin/ctnodered:latest

RUN     apk add --no-cache raspberrypi

you should remove - /opt/vc:/opt/vc:ro from compose file