Add Cryptocurrency proof of stake tutorial

README.md

@@ -81,6 +81,7 @@
 * [**Python**: _Let’s Build the Tiniest Blockchain_](https://medium.com/crypto-currently/lets-build-the-tiniest-blockchain-e70965a248b)
 * [**Ruby**: _Programming Blockchains Step-by-Step (Manuscripts Book Edition)_](https://github.com/yukimotopress/programming-blockchains-step-by-step)
 * [**TypeScript**: _Naivecoin: a tutorial for building a cryptocurrency_](https://lhartikk.github.io/)
+* [**TypeScript**: _NaivecoinStake: a tutorial for building a cryptocurrency with the Proof of Stake consensus_](https://naivecoinstake.learn.uno/)
 
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