Url parsing example (brianc#19)

* Added URL parsing example

* Typos and cleanup

* Last typo

Author: timhaley94

README.md

@@ -46,6 +46,40 @@ var PgNativeClient = require('pg-native')
 var pgNativePool = new Pool({ Client: PgNativeClient })
 ```
 
+##### Note:
+The Pool constructor does not support passing a Database URL as the parameter. To use pg-pool on heroku, for example, you need to parse the URL into a config object. Here is an example of how to parse a Database URL.
+
+```js
+const Pool = require('pg-pool');
+const url = require('url')
+
+const params = url.parse(process.env.DATABASE_URL);
+const auth = params.auth.split(':');
+
+const config = {
+  user: auth[0],
+  password: auth[1],
+  host: params.hostname,
+  port: params.port,
+  database: params.pathname.split('/')[1],
+  ssl: true
+};
+
+const pool = Pool(config);
+
+/*
+  Transforms, 'progres://DBuser:secret@DBHost:#####/myDB', into
+  config = {
+    user: 'DBuser',
+    password: 'secret',
+    host: 'DBHost',
+    port: '#####',
+    database: 'myDB',
+    ssl: true
+  }
+*/
+``` 
+
 ### acquire clients with a promise
 
 pg-pool supports a fully promise-based api for acquiring clients