Fix wrong method name in README example (#77)

* Fix wrong method name in README example

The method `getPriceData` does not exist on `EvmPriceServiceConnection`, I assume the example should use the method `getPriceFeedsData` instead:
https://github.com/pyth-network/pyth-js/blob/eadb2c5386ada06eb99b5b56cd7805d7fed713d9/pyth-evm-js/src/EvmPriceServiceConnection.ts#L12

* Fix wrong method name in comment

* Fix wrong variable name in example

Author: ckoopmann

pyth-evm-js/README.md

@@ -36,17 +36,17 @@ const priceIds = [
 ];
 
 // In order to use Pyth prices in your protocol you need to submit the price update data to Pyth contract in your target
-// chain. `getPriceUpdateData` creates the update data which can be submitted to your contract. Then your contract should
+// chain. `getPriceFeedsUpdateData` creates the update data which can be submitted to your contract. Then your contract should
 // call the Pyth Contract with this data.
-const priceUpdateData = await connection.getPriceUpdateData(priceIds);
+const priceUpdateData = await connection.getPriceFeedsUpdateData(priceIds);
 
 // If the user is paying the price update fee, you need to fetch it from the Pyth contract.
 // Please refer to https://docs.pyth.network/consume-data/on-demand#fees for more information.
 //
 // `pythContract` below is a web3.js contract; if you wish to use ethers, you need to change it accordingly.
 // You can find the Pyth interface ABI in @pythnetwork/pyth-sdk-solidity npm package.
 const updateFee = await pythContract.methods
-  .getUpdateFee(priceFeedUpdateData)
+  .getUpdateFee(priceUpdateData)
   .call();
 // Calling someContract method
 // `someContract` below is a web3.js contract; if you wish to use ethers, you need to change it accordingly.