diff --git a/doc/user-guide.md b/doc/user-guide.md
index b2983ee76c5..42503c808a7 100644
--- a/doc/user-guide.md
+++ b/doc/user-guide.md
@@ -106,6 +106,29 @@ After modifying the `*_types.go` file always run the following command to update
 $ operator-sdk generate k8s
 ```
 
+### OpenAPI validation
+To update the OpenAPI validation section in the CRD `deploy/crds/cache_v1alpha1_memcached_crd.yaml`, run the following command. 
+
+```console
+$ operator-sdk generate openapi
+```
+This validation section allows Kubernetes to validate the properties in a Memcached Custom Resource when it is created or updated. An example of the generated YAML is as follows: 
+
+```YAML
+spec:
+  validation:
+    openAPIV3Schema:
+      properties:
+        spec:
+          properties:
+            size:
+              format: int32
+              type: integer
+```
+
+To learn more about OpenAPI v3.0 validation schemas in Custom Resource Definitions, refer to the [Kubernetes Documentation][doc_validation_schema].
+
+
 ## Add a new Controller
 
 Add a new [Controller][controller-go-doc] to the project that will watch and reconcile the Memcached resource:
@@ -619,3 +642,4 @@ When the operator is not running in a cluster, the Manager will return an error
 [result_go_doc]: https://godoc.org/github.com/kubernetes-sigs/controller-runtime/pkg/reconcile#Result
 [metrics_doc]: ./user/metrics/README.md
 [quay_link]: https://quay.io
+[doc_validation_schema]: https://kubernetes.io/docs/tasks/access-kubernetes-api/custom-resources/custom-resource-definitions/#specifying-a-structural-schema