Fixed source code link for demos 📝

Author: Fzwael

docs/SUMMARY.md

@@ -22,7 +22,7 @@
       * [Outputs](api/detail/outputs.md)
 * Demos
     * [Online](http://swimlane.github.io/ngx-datatable/)
-    * [Source Code](https://github.com/swimlane/ngx-datatable/tree/master/demo)
+    * [Source Code](https://github.com/swimlane/ngx-datatable/tree/master/src/app)
 * Contributing
    * [Building](contributing/building.md)
    * [Guidelines](contributing/guidelines.md)