Update README and Project Method

Author: rossedman

README.md

@@ -311,6 +311,12 @@ Get time totals for a tasklist
 $teamwork->tasklist($id)->timeTotal();
 ```
 
+Get tasklists associated with a project
+
+```php
+$teamwork->project($id)->tasklists();
+```
+
 #### Milestone
 
 Get all milestones in Teamwork.

src/Rossedman/Teamwork/Project.php

@@ -144,7 +144,7 @@ public function milestones($args = null)
      *
      * @return [type] [description]
      */
-    public function tasklist($args = null)
+    public function tasklists($args = null)
     {
         return $this->client->get("$this->endpoint/$this->id/tasklists", $args)->response();
     }