message: docs: fix example image url
diff: @@ -109,7 +109,7 @@ Setting has been deployed!
  ```
  In this exapmle, JavaScript and CSS Customization is set as below.
  -![Example screenshot of JavaScript and CSS Customization](https://raw.githubusercontent.com/kintone/customize-uploader/master/docs/example_setting.PNG)
  +![Example screenshot of JavaScript and CSS Customization](docs/example_setting.PNG)
  ## LICENSE
  MIT License
  