modernleft-docs/Docker Images/quartz/use xxd in docker.md

docker run --rm -it alpine:latest sh

apk add xxd openssl

echo PDS_PLC_ROTATION_KEY_K256_PRIVATE_KEY_HEX: $(openssl ecparam --name secp256k1 --genkey --noout --outform DER | tail --bytes=+8 | head --bytes=32 | xxd --plain --cols 32)