chore: remove blockchain TLDR

Author: eros938

data/blog/blockchain-fundamentals-a-security-engineers-mental-model.mdx

@@ -16,16 +16,6 @@ If that sounds like you, good. By the end of this, you should be able to read an
 
 Let's get into it.
 
-## Blockchain Fundamentals Quick Answer (TL;DR)
-
-If you only have 2 minutes, anchor on these points:
-
-1. Blockchain is an append-only, replicated ledger secured by hashes, signatures, and consensus.
-2. Every block links to the previous block hash, so tampering breaks the chain.
-3. Consensus picks who writes the next block: Proof of Work (electricity) or Proof of Stake (locked capital).
-4. Your private key is your account; lose it or leak it, and funds are gone.
-5. Web3 security focuses on smart contracts, bridges, and key management.
-
 ## Who This Guide Is For
 
 - Security engineers and appsec folks learning Web3 from first principles