fix: Update PropagationPolicy comment as requested in review

Co-authored-by: circy9 <[email protected]>
Signed-off-by: Liqian Luo <[email protected]>

Author: Copilot

apis/placement/v1beta1/clusterresourceplacement_types.go

@@ -1325,7 +1325,7 @@ const (
 
 // DeleteStrategy configures the deletion behavior when a placement is deleted.
 type DeleteStrategy struct {
-	// PropagationPolicy controls whether to delete placed resources when the placement is deleted.
+	// PropagationPolicy controls whether to delete placed resources when placement is deleted.
 	//
 	// Available options:
 	//