Add updated Spanish translation.

[wilsenhc]

Hello, I am setting up and have been working for some time in a new & updated Spanish translation of this book.

It has been forked from the original translation which is outdated, and then updated to the latest/current version of the book.

Currently we're sitting at more than 50% of the chapters translated.

It would be great if we could set this up with a subdomain for better visibility like: es.phptherightway.com.

I have already setup the CNAME in the my own repo, and would only have to update the baseUrl variables to work with the subdomain, etc.

Currently you can look at the progress of the translation here: https://wilsenhc.github.io/php-the-right-way/

You can take a look at the repo and the progress of the translation in the list of open issues: https://github.com/wilsenhc/php-the-right-way/issues

I would like to thanks @vicmans, @DesolatorMagno, @paulohbsousa, @abr4xas for all the help they provided with this translation 🚀