Add Link for "Operator White Paper".

Author: Shubham82

content/en/docs/concepts/extend-kubernetes/operator.md

@@ -124,6 +124,7 @@ Operator.
 ## {{% heading "whatsnext" %}}
 
 
+* Learn about [operator white paper](https://github.com/cncf/tag-app-delivery/blob/eece8f7307f2970f46f100f51932db106db46968/operator-wg/whitepaper/Operator-WhitePaper_v1-0.md)
 * Learn more about [Custom Resources](/docs/concepts/extend-kubernetes/api-extension/custom-resources/)
 * Find ready-made operators on [OperatorHub.io](https://operatorhub.io/) to suit your use case
 * [Publish](https://operatorhub.io/) your operator for other people to use