Update 'README.md'

README.md

@@ -26,6 +26,7 @@ ___
 - [Desmos](https://www.desmos.com/calculator)
 - [Detexify](http://detexify.kirelabs.org/classify.html)
 - [Computational Complexity Zoo](https://complexityzoo.net/Complexity_Zoo)
+- [Backlog](backlog.md)
 
 ## [Reading Stack](backlog.md)
 - [Post-quantum cryptography](https://www.nature.com/articles/nature23461)