[Docs] Fix examples for empty keys parsing

Author: Coobaha

README.md

@@ -306,14 +306,14 @@ By default, empty keys are omitted after parsing:
 
 ```javascript
 var obj = qs.parse("=1&=2");
-assert.deepEqual(withNull, {});
+assert.deepEqual(obj, {});
 ```
 
 It is possible to include empty keys by using `allowEmptyKeys` flag:
 
 ```javascript
 var obj = qs.parse("=1&=2", { allowEmptyKeys: true });
-assert.deepEqual(withNull, { "": ["1","2"] });
+assert.deepEqual(obj, { "": ["1","2"] });
 ```
 
 ### Stringifying