Add currency symbols like "€" or "$" to country codes

[erf]

I would like to see currency symbols in https://datahub.io/core/country-codes

E.g. "$" for USD, "€" for EUR, or "kr" for NOK

See: https://www.xe.com/symbols.php

https://gist.github.com/Chintan7027/fc4708d8b5c8d1639a7c