README needs a correction about generating the pem

[benbonnet]

not sure if I did some wrong somewhere or if there is an obvious thing to know in order to correct it, but I could not have the example working with how you tell to build the .pem file. That said, your online example you provide does not work; it might be the reason

Instead, it did worked with the command line google tells you to run ( here https://cloud.google.com/storage/docs/authentication on the "Converting the service account credential to other formats" part) :

$ cat /path/to/xxxx-privatekey.p12 | openssl pkcs12 -nodes -nocerts -passin pass:notasecret | openssl rsa > /path/to/secret.pem

Thanks for this package, put me on the path

Best regards