add screen-shot of design exception

src/guides/v2.3/frontend-dev-guide/themes/theme-apply.md

@@ -43,6 +43,9 @@ To add a design exception:
 1. In the configuration record corresponding to your store view, click **Edit**.
 1. On the **Design Rule** tab, click **Add New User Agent Rule**.
 1. In the **Search String** box specify the user-agent using either normal strings or regular expressions (PCRE). In the **Theme Name** drop-down list select the theme to be used for matching agent.
+
+![Design Exception]({{ site.baseurl }}/common/images/user_agent_rule.png)
+
 1. Click **Save Configuration** or **Save and Continue**.
 1. If caching is enabled, [clear the cache](#theme-apply-clear).
 1. To see your changes applied, reload the storefront pages.
@@ -81,4 +84,4 @@ A system message notifies you that invalidated cache types must be refreshed.
 If the changes you configure in the Admin are not applied after you clear the cache and reload the page, delete all files in the `pub/static/frontend` and `var/view_preprocessed` directories, then reload the pages. You can delete the files manually or run the `grunt clean:<theme_name>` command in CLI. For details about using Grunt in Magento see [Installing and configuring Grunt]({{ page.baseurl }}/frontend-dev-guide/css-topics/css_debug.html#prerequisites).
 
 [Design Configuration page]: {{site.baseurl}}/common/images/design_conf1.png
-[Design Configuration page for a particular scope]: {{site.baseurl}}/common/images/fdg/applied_theme.png
+[Design Configuration page for a particular scope]: {{site.baseurl}}/common/images/fdg/applied_theme.png