docs(README): switch to Sepolia network

README.md

@@ -48,8 +48,8 @@ The complete examples with various use cases are available [here](https://github
 import { Provider, utils, types } from "zksync-ethers";
 import { ethers } from "ethers";
 
-const provider = Provider.getDefaultProvider(types.Network.Goerli); // zkSync Era testnet (L2)
-const ethProvider = ethers.getDefaultProvider("goerli"); // goerli testnet (L1)
+const provider = Provider.getDefaultProvider(types.Network.Sepolia); // zkSync Era testnet (L2)
+const ethProvider = ethers.getDefaultProvider("sepolia"); // Sepolia testnet (L1)
 ```
 
 ### Get the latest block number