Update free-courses-en.md (#4751)

* Update free-courses-en.md

* Update free-courses-en.md

free-courses-en.md

@@ -266,13 +266,16 @@
 * [CSS Flexbox - Mastering the Basics](https://www.udemy.com/css-flexbox-mastering-the-basics/) - Vishwas Gopinath (Udemy)
 * [CSS Grid](https://cssgrid.io) - Wesbos
 * [CSS Tutorial](https://www.youtube.com/playlist?list=PL_RGaFnxSHWqMH9a9DY8LFKrJ5NJCFHHe)
+* [CSS3 tutorial for beginners | Learn CSS3](https://www.udemy.com/course/css3-tutorial-for-beginners-learn-css3/) - Udemy
 * [Flexbox in 30 Days](https://github.com/samanthaming/Flexbox30) - Samantha Ming
 * [HTML and CSS Crash Course](https://scrimba.com/learn/htmlcss) - Kevin Powell (scrimba)
 * [HTML Tutorial](https://www.youtube.com/playlist?list=PL_RGaFnxSHWr_FB-hVEgEGUESZL1TOiJ6)
 * [Learn how to program: CSS](https://www.learnhowtoprogram.com/css) - Epicodus Inc.
 * [Learn HTML5 Programming From Scratch](https://www.udemy.com/learn-html5-programming-from-scratch/)
 * [Learn to style HTML using CSS](https://developer.mozilla.org/en-US/docs/Learn/CSS)
+* [Responsive Web Design with HTML5 and CSS3 - Advanced](https://www.udemy.com/course/responsive-web-design-with-html5-and-css3-advanced/) - Udemy
 * [Structuring the web with HTML](https://developer.mozilla.org/en-US/docs/Learn/HTML)
+* [Web Development By Doing: HTML / CSS From Scratch](https://www.udemy.com/course/web-development-learn-by-doing-html5-css3-from-scratch-introductory/) - Udemy
 * [What the Flexbox](https://flexbox.io) - Wesbos
 
 
@@ -556,6 +559,7 @@
 
 * [Learn how to program: Ruby](https://www.learnhowtoprogram.com/ruby) - Epicodus Inc.
 * [Learn Ruby](https://www.learnrubyonline.org)
+* [RESTful API with Ruby On Rails 5](https://www.udemy.com/course/restful-api-with-ruby-on-rails-5/) - Udemy
 * [Ruby Tutorial](https://www.w3resource.com/ruby/)
 * [RubyMonk - Interactive Ruby tutorials](https://rubymonk.com)