Update CHANGELOG.md

Author: ryanio

CHANGELOG.md

@@ -23,7 +23,7 @@ import { Account, BN } from 'ethereumjs-util'
 
 const account = new Account(
  new BN(0), // nonce, default: 0
- new BN(10).pow(18), // balance, default: 0
+ new BN(10).pow(new BN(18)), // balance, default: 0
  undefined, // stateRoot, default: KECCAK256_RLP (hash of RLP of null)
  undefined, // codeHash, default: KECCAK256_NULL (hash of null)
 )