docs: add GitHub App setup screenshot

Author: ZIJ

docs/ce/self-host/deploy-helm.mdx

@@ -152,6 +152,8 @@ description: "Learn how to use Helm chart to install Digger on your Kubernetes c
        - Client Secret
        - Private Key (base64 encoded)
        - Webhook Secret
+    
+    ![Digger GitHub App Setup Success](/images/digger-github-app-wizard.png)
   </Step>
 
   <Step title="Update configuration with GitHub App credentials">