Add chain.resourses (#6358)

Author: atishaye

books/free-programming-books-subjects.md

@@ -137,6 +137,7 @@ Books that cover a specific programming language can be found in the  [BY PROGRA
 
 * [Bitcoin and Cryptocurrency Technologies](http://bitcoinbook.cs.princeton.edu) - Arvind Narayanan, Joseph Bonneau, Edward Felten, Andrew Miller, Steven Goldfeder, Jeremy Clark (PDF)
 * [Blockchain for Dummies, 2nd IBM Limited Edition](https://www.ibm.com/downloads/cas/36KBMBOG) - Manav Gupta (PDF)
+* [chain.courses](https://chain.courses) - James Gan, Rishub Kumar
 * [Getting Started with Enterprise Blockchain: A Guide to Design and Development](https://www.ibm.com/downloads/cas/RYWXAR0M) - Michael Bradley, David Gorman, Matt Lucas, Matthew Golby-Kirk (PDF)
 * [IBM Blockchain: The Founder’s Handbook, Third Edition](https://www.ibm.com/downloads/cas/GZPPMWM5) - Antonio Banda, Matthew Hamilton, Eileen Lowry, John Widdifield et al. (PDF)
 * [Mastering Bitcoin - Unlocking digital currencies](https://github.com/bitcoinbook/bitcoinbook) - Andreas M. Antonopoulos