Update es.json (#1139)

The use of the word "Subscribir" is updated by "Suscribir", because it is the form recommended by the RAE:
https://dle.rae.es/suscribir?m=form

The use of the word "Des-subscribir" is updated, since its use is wrong. The RAE recommends the use of "Darse de baja":
https://twitter.com/raeinforma/status/748125040722448384?lang=es