Adds zkSync Era Withdrawal Finalizer to list of users in README.md (gakonst#2673)

Author: montekki

README.md

@@ -209,6 +209,7 @@ You can get one [here](https://etherscan.io/apis).
 -   [Celo Plumo Prover](https://github.com/celo-org/plumo-prover): Creates Celo's ultralight client proof from on-chain data
 -   [Celo SNARK Setup Coordinator](https://github.com/celo-org/snark-setup-operator): Coordinator for executing a pipelined Groth16 SNARK setup
 -   [ERC-4337 Bundler](https://github.com/Vid201/aa-bundler/): Account Abstraction (ERC-4337) bundler
+-   [zkSync Withdrawal Finalizer](https://github.com/matter-labs/zksync-withdrawal-finalizer): Finalizer of withdrawals from zkSync Era to L1.
 
 ## Credits