Add linux book (#6768)

* Add Arduino books

* Update books/free-programming-books-pt_BR.md

Co-authored-by: ImVector <59611597+LuigiImVector@users.noreply.github.com>

* Remove Eletrogate books and add a new one

* Change book's author.

* Removing link of the book

* Removing journal and edit the link

* Add a new book about Linux

* Update books/free-programming-books-pt_BR.md

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

Co-authored-by: ImVector <59611597+LuigiImVector@users.noreply.github.com>
Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

books/free-programming-books-pt_BR.md

@@ -75,6 +75,7 @@
 
 #### Sistemas Operacionais
 
+* [Guia com mais de 500 comandos do Linux explicados](https://www.gnulinuxbrasil.com.br/2017/05/24/guia-com-mais-de-500-comandos-do-linux-explicados/) - Bruno Andrade (PDF)
 * [Guia Foca Linux](https://www.guiafoca.org/#download) - Gleydson Maziolli (PDF)
 * [Sistemas Operacionais: Conceitos e Mecanismos](http://wiki.inf.ufpr.br/maziero/lib/exe/fetch.php?media=socm:socm-livro.pdf) - Carlos A. Maziero (PDF) (:construction: *em contínuo desenvolvimento*)