modify README.md

README.md

@@ -11,6 +11,7 @@ Install with:
 
 ## Usage Example
 
+### Create Client
 ```js
 var clientConfig = {
     bucketUri: 's3://xxxx'
@@ -22,24 +23,30 @@ var awsConfig = {
 
 var athena = require("athena-client")
 var client = athena.createClient(clientConfig, awsConfig)
+```
 
-// receive result by callback
+### Receive result by Callback
+```js
 client.execute('SELECT 1', function(err, data) {
     if (err) {
         return console.error(err)
     }
     console.log(data)
 })
-
-// receive result by promise
+```
+
+### Receive result by Promise
+```js 
 client.execute('SELECT 1').toPromise()
 .then(function(data) {
     console.log(data)
 }).catch(function(err) {
     console.error(err)
 })
+```
 
-// receive result by stream
+### Receive result by Stream
+```js
 var stream = client.execute('SELECT 1').toStream()
 stream.on('data', (record) => {
   console.log(record)