little document update clarify steps to be able to run the example
MODIFY
examples/node/README.md
examples/node/README.md
git clone git@github.com:maticnetwork/matic.js.git
```
+
+
+### Edit config.js
+```
+PRIVATE_KEY: '<paste your private key here>', // A sample private key prefix with `0x`
+FROM_ADDRESS: '<paste address belonging to private key here>',// Your address
+```
+Update following lines with your wallet address and key.
+Be careful with your private key, Use a key your are comfortable with for development purpose.
+
### Install and run:
```bash
cd examples/node
npm install
node balance-of-ERC20.js
\ No newline at end of file
-```

little document update clarify steps to be able to run the example