No amd64 docker image available

Since version 0.5.0, the official docker image has only been built for the `linux/arm64` architecture. Not sure whether that's intentional, but I'd appreciate a `linux/amd64` image


Also, the link in the README currently points to your "private" URL. It should point to this instead: https://hub.docker.com/r/anasaso/ssllabs_exporter