Update chapter3

Author: nayunhwan

chapter3.md

@@ -59,3 +59,6 @@ export class AppComponent {
 ![](./assets/capture/clickButton2.png)
 
 정상적으로 `Alert`창이 표시된다면 잘따라오신 것입니다!
+
+### [이전 게시물 :: Setup Libraries](chapter2.md)
+### [다음 게시물 :: Build Structure](chapter4.md)