Add tutorial rails girls (#4484)

* Add tutorial rails girls

* Add Rails Girls tutorial as requested in #4484

* Updated commit as requested in #4484

free-courses-pt_BR.md

@@ -226,6 +226,7 @@
 * [Ruby on Rails 5 na Prática](https://www.udemy.com/ruby-on-rails-5-na-pratica/) - Bruno Paulino (Udemy)
 * [Ruby Para Iniciantes](https://www.udemy.com/ruby-para-iniciantes/) - Bruno Paulino (Udemy)
 * [Ruby Puro](https://onebitcode.com/course/ruby-puro/) - One Bit Code (Site One Bit Code)
+* [Tutorial Rails Girls](http://guides.railsgirls.com/guides-ptbr/)
 
 
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