Create README.es-ES.md for spanish documentation

[rpalaciosg]

Hi, I would like to know if you think its a good idea create a README.es-ES.md file for the spanish translation of the documentation?

I have a PR #35 in draft that you could review.

[Lugriz]

Hi @rpalaciosg!

I think it's a good idea to add it. Thanks for you interest to contribute to this library.