Spanish translation

Hi! I'm interested in helping translating the project into Spanish and I was wondering if I could start pull requests of the files. Many thanks in advance!

[goodfeli]

It's fine to translate this repository with just the notation page into Spanish. If you want to translate the whole book, you'll need to get permission from the owner of the rights. Our contract gave the rights to MIT Press, and MIT Press has probably sold the Spanish translation rights to a publisher who focuses on Spanish.