add Español (Spanish) translation of the docs

Thanks @AlbertoFuente!

Author: sindresorhus

contributing.md

@@ -2,7 +2,7 @@
 
 ✨ Thanks for contributing to AVA! ✨
 
-Translations: [Français](https://github.com/sindresorhus/ava-docs/blob/master/fr_FR/contributing.md)
+Translations: [Español](https://github.com/sindresorhus/ava-docs/blob/master/es_ES/contributing.md), [Français](https://github.com/sindresorhus/ava-docs/blob/master/fr_FR/contributing.md)
 
 ## How can I contribute?
 

readme.md

@@ -8,7 +8,7 @@ Even though JavaScript is single-threaded, IO in Node.js can happen in parallel
 
 *Read our [contributing guide](contributing.md) if you're looking to contribute (issues/PRs/etc).*
 
-Translations: [Français](https://github.com/sindresorhus/ava-docs/blob/master/fr_FR/readme.md)
+Translations: [Español](https://github.com/sindresorhus/ava-docs/blob/master/es_ES/readme.md), [Français](https://github.com/sindresorhus/ava-docs/blob/master/fr_FR/readme.md)
 
 
 ## Table of Contents