Update courses.md (#500)

Adds cyfrin updraft to courses list

docs/courses/courses.md

@@ -4,6 +4,9 @@ sidebar_position: 1
 
 # Learning Platforms
 
+- [Cyfrin Updraft](https://updraft.cyfrin.io) Cyfrin Updraft is the leading smart contract development and security learning platform. With 50+ hours of courses and 300 videos and written lessons, to go from zero to blockchain hero, completely for free.
+
+Completely free and open-sourced!
 - [LearnWeb3](https://learnweb3.io) LearnWeb3 is the best, fastest-growing, and completely free web3 education platform for new and experienced web2 developers.
 
 - [Crypto Zombies](https://cryptozombies.io/) CryptoZombies is an interactive school that teaches you all things technical about blockchains. Learn to write smart contracts by making your own crypto-collectibles game.