* Update free-courses-en.md

Added Flexbox & CSS Grid free video resources to the repo

* Update free-courses-en.md

* Update free-courses-en.md

Removed the trailing slashes from the root domain

* Update free-courses-en.md

Added free Javascript30 course from Wesbos

* Markdown video course

Added free Markdown video course

* Update free-courses-en.md

* Update free-programming-books.md

Added a free markdown resource that covers all the basics concepts