Corrected a few tiny typos in Spanish translation

- from "fué" to "fue"
- from "Asegúrese que las tablas " to "Asegúrese de que las tablas " 
- from ", y que la base de datos" to ", y de que la base de datos"
- from "Entre" to "Introduzca"
- from "invalido" to "inválido"
- from "porqué" to "porque"