It's a well-written practical demonstration of an interesting thing that [some people might not know about yet][0], with links for further reading. What's the problem?
Still, didn't seem very novel or deep. Might as well have been someone posting their first timing circuit test, water/air tunnel simulation, or computer vision project. So, good for them. But I thought HN wasn't a glad handing cheerleader chorus.
Searching for Introduction to Markov Chains gets tons of hits at various levels of explanation that are nearly a decade old.