enable spanish lang and update readme

[mariacastiel]

I attempted to rebase from master but it all went kaboom, so i have only made changes to the files I think are needed to get the Spanish translation enabled. This is important for translators to see the result of their translations and self-learn while translating.

[darigovresearch]

Think having translations for the academy would be incredibly helpful. The deploy preview has a nice button to be able to switch languages and this could help create momentum for a community-led translation contributions