Saving Certificate Example Broken

The example given in the readme for saving certificates:

$ docker run -d \
-v $(pwd)/Caddyfile:/etc/Caddyfile \
-v $HOME/.caddy:/root/.caddy \
-p 80:80 -p 443:443 \
abiosoft/caddy

Fails with:

docker: Error response from daemon: OCI runtime create failed: container_linux.go:349: starting container process caused "process_linux.go:449: container init caused \"rootfs_linux.go:58: mounting \\\"/root/Caddyfile\\\" to rootfs \\\"/var/lib/docker/overlay2/f21bf427bff77dcb48803f99ade87807a8cf783e316efdcd938d5678c3cdd57d/merged\\\" at \\\"/var/lib/docker/overlay2/f21bf427bff77dcb48803f99ade87807a8cf783e316efdcd938d5678c3cdd57d/merged/etc/Caddyfile\\\" caused \\\"not a directory\\\"\"": unknown: Are you trying to mount a directory onto a file (or vice-versa)? Check if the specified host path exists and is the expected type.