Fix: Quote newTag in kustomization.yaml example to avoid YAML error

Author: intojhanurag

content/en/docs/tasks/manage-kubernetes-objects/kustomization.md

@@ -739,7 +739,7 @@ resources:
 images:
 - name: nginx
   newName: my.image.registry/nginx
-  newTag: 1.4.0
+  newTag: "1.4.0"
 EOF
 ```