Update free-courses-pt_BR.md (#3224)

free-courses-pt_BR.md

@@ -1,6 +1,7 @@
 ### Index
 
 * [Android](#android)
+* [CSS](#css)
 * [Dart](#dart)
 * [Git](#git)
 * [Go](#go)
@@ -19,6 +20,11 @@
 * [Desenvolvedor Android Iniciante](https://www.udemy.com/desenvolvedor-android-iniciante/) - Gabriel Ferrari, Adriano Sacardo (Udemy)
 
 
+### CSS
+
+* [Introdução à linguagem CSS](https://www.udemy.com/introducao-a-linguagem-css/) - Diego Mariano (Udemy)
+
+
 ### Dart
 
 * [Curso de Dart Lang](https://www.udemy.com/curso-de-dart-lang-completo/) - Sthefane Soares (Udemy)