Remove dead link (#5230)

This video isn't available any more

src/data/roadmaps/blockchain/content/101-blockchain-general-knowledge/103-blockchain-forking.md

@@ -7,4 +7,3 @@ Visit the following resources to learn more:
 - [Blockchain Fork](<https://en.wikipedia.org/wiki/Fork_(blockchain)>)
 - [What is a fork?](https://www.coinbase.com/learn/crypto-basics/what-is-a-fork)
 - [What Is a Hard Fork?](https://www.investopedia.com/terms/h/hard-fork.asp)
-- [Blockchain Forking](https://www.youtube.com/watch?v=bu1gcyyfz7w)