message: Add MIT attribution for proof_util.ts
diff: @@ -8,6 +8,8 @@ const rlp = ethUtils.rlp;
  import EthereumBlock from 'ethereumjs-block/from-rpc';
  import { Converter, promiseResolve, utils } from "..";
  +// Implementation adapted from Tom French's `matic-proofs` library used under MIT License
  +// https://github.com/TomAFrench/matic-proofs
  export class ProofUtil {
  