Add Scrum Manager BoK books (#4487)

Signed-off-by: Francisco Javier Llanquipichun Garcia <francisco.llanquipichun@gmail.com>

free-programming-books-es.md

@@ -104,6 +104,8 @@
 * [Diseño Ágil con TDD](http://www.carlosble.com/downloads/disenoAgilConTdd_ebook.pdf) (PDF)
 * [Ingeniería de Software: Una Guía para Crear Sistemas de Información](https://web.archive.org/web/20150824055042/http://www.wolnm.org/apa/articulos/Ingenieria_Software.pdf) (PDF)
 * [Scrum & Extreme Programming (para programadores)](https://web.archive.org/web/20140209204645/http://www.cursosdeprogramacionadistancia.com/static/pdf/material-sin-personalizar-agile.pdf) (PDF)
+* [Scrum Level](https://scrumlevel.com/files/scrumlevel.pdf) - Scrum Manager (PDF) [(EPUB)](https://scrumlevel.com/files/scrumlevel.epub)
+* [Scrum Master - Temario troncal 1](https://scrummanager.net/files/scrum_master.pdf) - Scrum Manager (PDF) [(EPUB)](https://scrummanager.net/files/scrum_master.epub)
 * [Scrum y XP desde las trincheras](http://www.proyectalis.com/wp-content/uploads/2008/02/scrum-y-xp-desde-las-trincheras.pdf) (PDF)