Update readme (brianc#1210)

* Fix sample code in README

* Fix typo

Author: pataiadam

README.md

@@ -83,8 +83,8 @@ pool.connect(function(err, client, done) {
     return console.error('error fetching client from pool', err);
   }
   client.query('SELECT $1::int AS number', ['1'], function(err, result) {
-    //call `done()` to release the client back to the pool
-    done();
+    //call `done(err)` to release the client back to the pool (or destroy it if there is an error)
+    done(err);
 
     if(err) {
       return console.error('error running query', err);