Translated Week5-Using_-Lecture. Close #395.
Several edits. refs #395.
Minor edit. refs #395.
Edits according to comments. refs #395.
FTS to Búsqueda de texto completo. refs #395.
Minor edits. (refs #395).
Merge pull request #408 from puentesarrin/issue-395

Translated Week5-Using_$text-Lecture. Close #395.