Documentation improvement

[g00nix]

Hey,

This can be added to .zshrc to automate the use of the tool:

nom_to_png() {
    cat $1 | docker run -i dapariscode/nomnoml-cli /bin/bash -c "cat | ./nomnoml" > $1.png.tmp
    mv $1.png.tmp $1.png
}

If you consider this useful, please add it to documentation. It helped me a lot.

Best Regards!