* Adding "Computação: Matemática Discreta" book

Great book for learning discrete mathematics in poruguese, from Raquel Montezuma and should definitely be on this GH Repo.

* Update books/free-programming-books-pt_BR.md
Co-authored-by: NImVector <59611597+LuigiImVector@users.noreply.github.com>
Co-authored-by: NImVector <59611597+LuigiImVector@users.noreply.github.com>