Update README for podvm image creation

Signed-off-by: Pradipta Banerjee <pradipta.banerjee@gmail.com>

config/peerpods/podvm/README.md

@@ -11,19 +11,25 @@ The configuration used for the podvm image generation is available in the follow
 
 Depending on the cloud provider (eg. aws or azure) create the respective
 configmaps. Please review and modify the settings in the configMap as required.
+For example, if you need to add NVIDIA GPU drivers in the podvm image then set
+`ENABLE_NVIDIA_GPU: yes`. Likewise if you want to create image for
+confidential containers then set `CONFIDENTIAL_COMPUTE_ENABLED: yes`.
 
-For AWS
+Use the following command to create the configMap for AWS:
 
 ```sh
 kubectl apply -f aws-podvm-image-cm.yaml
 ```
 
-For Azure
+Use the following command to create the configMap for Azure:
 
 ```sh
 kubectl apply -f azure-podvm-image-cm.yaml
 ```
 
+Note: You must update the `IMAGE_GALLERY_NAME` with a gallery name in `azure-podvm-image-cm` configMap.
+If the gallery name doesn't exist then it'll be created.
+
 ## Create podvm image
 
 The podvm image is created in a Kubernetes job. To create the job run the following command
@@ -35,7 +41,7 @@ kubectl apply -f osc-podvm-create-job.yaml
 On successful image creation, the podvm image details will be updated as an annotation in the `peer-pods-cm`
 under `openshift-sandboxed-containers-operator` namespace.
 
-The annotation key for AWS is `LATEST_AMI_ID` and for Azure it's `LATEST_IMAGE_ID`
+The annotation key for AWS is `LATEST_AMI_ID` and for Azure it's `LATEST_IMAGE_ID`.
 
 ## Delete podvm image
 
@@ -44,3 +50,5 @@ Update the IMAGE_ID for Azure or AMI_ID for AWS that you want to delete and then
 ```sh
 kubectl delete -f osc-podvm-delete-job.yaml
 ```
+If you want to delete the associated gallery (in Azure) then add `-g` option to the command.
+The updated command will be `["/podvm-builder.sh", "delete", "-f", "-g"]