docs: Add note on the requirements of resource templates. Fixes #5566 (…

…#6125)

Signed-off-by: Yuan Tang <terrytangyuan@gmail.com>

examples/README.md

@@ -1431,6 +1431,9 @@ spec:
           backoffLimit: 4
 ```
 
+**Note:**
+Currently only a single resource can be managed by a resource template so either a `generateName` or `name` must be provided in the resource's metadata.
+
 Resources created in this way are independent of the workflow. If you want the resource to be deleted when the workflow is deleted then you can use [Kubernetes garbage collection](https://kubernetes.io/docs/concepts/workloads/controllers/garbage-collection/) with the workflow resource as an owner reference ([example](./k8s-owner-reference.yaml)).
 
 **Note:**