Add create image policy examples

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

cmd/flux/create_image_repository.go

@@ -30,7 +30,7 @@ import (
 )
 
 var createImageRepositoryCmd = &cobra.Command{
-	Use:   "repository <name>",
+	Use:   "repository [name]",
 	Short: "Create or update an ImageRepository object",
 	Long: `The create image repository command generates an ImageRepository resource.
 An ImageRepository object specifies an image repository to scan.`,