Update README.md

Author: dtaipov

README.md

@@ -63,8 +63,7 @@ npm install keychain.js
 ```javascript
 const { Keychain, KeychainWeb3 } = require('keychain.js');
 const Web3 = require('web3');
-const API_URL = 'YOUR_API_URL'; // https://ropsten.infura.io/v3/046804e3dd3240b09834531326f310cf
-const web3 = new Web3(API_URL);
+const web3 = new Web3('YOUR_API_URL'); // https://ropsten.infura.io/v3/046804e3dd3240b09834531326f310cf
 const transactionParams = {
   to: '0xE8899BA12578d60e4D0683a596EDaCbC85eC18CC',
   value: 100,