docs: Updated Deployment Guide

Author: Avijit-Microsoft

docs/DeploymentGuide.md

@@ -138,7 +138,15 @@ Select one of the following options to deploy the Content Processing Solution Ac
     - Keep my existing files unchanged
     ```
     Choose “**Overwrite with versions from template**” and provide a unique environment name when prompted.
-6. Proceed to [Step 3: Configure Deployment Settings](#step-3-configure-deployment-settings)
+
+6. **Authenticate with Azure** (VS Code Web requires device code authentication):
+   
+    ```shell
+    az login --use-device-code
+    ```
+    > **Note:** In VS Code Web environment, the regular `az login` command may fail. Use the `--use-device-code` flag to authenticate via device code flow. Follow the prompts in the terminal to complete authentication.
+    
+7. Proceed to [Step 3: Configure Deployment Settings](#step-3-configure-deployment-settings)
 
 </details>
 
@@ -544,4 +552,4 @@ Run the build and push script for your operating system:
 ./infra/scripts/docker-build.ps1
 ```
 
-> **Note:** These scripts will deploy your local code changes instead of pulling from the GitHub repository.
+> **Note:** These scripts will deploy your local code changes instead of pulling from the GitHub repository.