Add detailed comments explaining state voiding behavior

Co-authored-by: vhvb1989 <24213737+vhvb1989@users.noreply.github.com>

Author: Copilot

cli/azd/pkg/infra/provisioning/bicep/bicep_provider.go

@@ -829,8 +829,10 @@ func (p *BicepProvider) Destroy(
 		return nil, fmt.Errorf("mapping resources to resource groups: %w", err)
 	}
 
-	// If no resources found, we still need to void the deployment state
-	// This can happen when resources have been manually deleted
+	// If no resources found, we still need to void the deployment state.
+	// This can happen when resources have been manually deleted before running azd down.
+	// Voiding the state ensures that subsequent azd provision commands work correctly
+	// by creating a new empty deployment that becomes the last successful deployment.
 	if len(groupedResources) == 0 {
 		p.console.StopSpinner(ctx, "", input.StepDone)
 		// Call deployment.Delete to void the state even though there are no resources to delete