fixed documentation

Author: craigphares

README.md

@@ -102,7 +102,7 @@ Use limit to specify the number of records to be retrieved, and use offset to sp
 
 ```php
 // Retrieve 5 models.
-$todos = $this->todo_model->limit(5);
+$todos = $this->todo_model->limit(5)->all();
 
 // Retrieve 5 models, starting at the 31st.
 $todos = $this->todo_model->limit(5)->offset(30)->all();