Update README.md

Author: takuya

README.md

@@ -68,7 +68,13 @@ foreach ($cli->space()->projects(Backlog::PROJECTS_ONLY_MINE) as $prj){
   }
 }
 ```
-自動補完の例
+## 自動補完の例
+BacklogのAPIのメソッド名を自動補完します。
+```
+$cli = new BacklogAPIClient($space, $key);
+$cli->...
+```
+
 <div>
 <img width="100%" alt="image" src="https://user-images.githubusercontent.com/55338/215521858-31d7fd22-ddd5-484f-b55f-af12503eb82a.png">
 </div>