DataMind is a website offering free tutorials for the R programming language and tools that let you develop your own tutorials based on R Markdown. I have not tested any of this, but it looks interesting.
Jonathan Cornelissen, Dieter De Mesmaeker, Martijn Theuwissen, Bram Jans, Albert Jorrisen. DatMind Beta. Excerpt: “Our mission is to empower everyone to become a data analytics expert for free! To achieve that, we are and will be working non-stop to deliver anyone, teacher and student, with the best learning experience for data science and statistics.” Available in html format.