Spanish translation for Rails 6 version

[oscartzgz]

Hi! in the last week I work on tutorial translation for Spanish version, I did it only with Rails 6 version.

[madeindjs]

First of all: thank you very much for your work !

I make two little comments. I also see two things to update:

• add es lang in rakefile: https://github.com/madeindjs/api_on_rails/blob/master/Rakefile#L4
• upload the book on leanpubas YOUR book version and add a link https://github.com/madeindjs/api_on_rails#support-the-project (if you want it of course)
• add a section "contributor" ith your name on readme: https://github.com/madeindjs/api_on_rails#license :)

[madeindjs]

Don't hesitate to add you name here :)

[madeindjs]

This tag seem be broken

[oscartzgz]

Thank you for your comments :)
I reviewed all your recommendations, I attended them and now I think everything is ready

[madeindjs]

Thank you for your work. I merge changes and create a new release on github.