Spanish translation

Hello,

thanks for this application. I've been using it for some time and it's quite useful in different situations.

I would like to provide a translation for Spanish, so people here can use it in a friendlier way. I've seen the files in `/src/assets
/i18n/`. Is it okay if I only create the `es.json` with the proper translations and then I open a PR?

Kind regards,

Felipe