refactor(optimistic-rollups): update op rollup fees section to match 4844 specs

Author: iankressin

public/content/developers/docs/scaling/optimistic-rollups/index.md

@@ -198,9 +198,9 @@ Finally, we should note that L2 > L1 message calls between contracts need to acc
 
 Optimistic rollups use a gas fee scheme, much like Ethereum, to denote how much users pay per transaction. Fees charged on optimistic rollups depends on the following components:
 
-1. **State write**: Optimistic rollups publish transaction data and block headers (consisting of the previous block header hash, state root, batch root) to Ethereum as `calldata`. The minimum cost of an Ethereum transaction is 21,000 gas. Optimistic rollups can reduce the cost of writing the transaction to L1 by batching multiple transactions in a single block (which amortizes the 21k gas over multiple user transactions).
+1. **State write**: Optimistic rollups publish transaction data and block headers (consisting of the previous block header hash, state root, batch root) to Ethereum as `blobs`. [EIP-4844](https://eips.ethereum.org/EIPS/eip-4844) introduced a cost-effective solution for including data on-chain. `blobs` is a new transaction field that allows rollups to post compressed state transition data to Ethereum L1 Unlike `calldata`, which remains permanently on-chain, blobs are short-lived and can be pruned from clients after [4096 epochs](https://github.com/ethereum/consensus-specs/blob/81f3ea8322aff6b9fb15132d050f8f98b16bdba4/configs/mainnet.yaml#L147) (approximately 18 days). By using `blobs` to post batches of compressed transactions, Optimistic rollups can significantly reduce the cost of writing transactions to L1.
 
-2. **`calldata`**: Beyond the base transaction fee, the cost of each state write depends on the size of `calldata` posted to L1. `calldata` costs are currently governed by [EIP-1559](https://eips.ethereum.org/EIPS/eip-1559), which stipulates a cost of 16 gas for non-zero bytes and 4 gas for zero bytes of `calldata`, respectively. To reduce user fees, rollup operators compress transactions to reduce the number of `calldata` bytes published on Ethereum.
+2. **Blob gas used**: Blob-carrying transactions employ a dynamic fee mechanism similar to the one introduced by [EIP-1559](https://eips.ethereum.org/EIPS/eip-1559). The gas fee for type-3 transactions takes into account the base fee for blobs, which is determined by the network based on blob-space demand and the blob-space usage of the transaction being sent.
 
 3. **L2 operator fees**: This is the amount paid to the rollup nodes as compensation for computational costs incurred in processing transactions, much like gas fees on Ethereum. Rollup nodes charge lower transaction fees since L2s have higher processing capacities and aren't faced with the network congestions that force validators on Ethereum to prioritize transactions with higher fees.