Update assumptions on run bundle-upgrade to include a scenario (#4968)

Signed-off-by: rashmigottipati <[email protected]>

Author: rashmigottipati

website/content/en/docs/olm-integration/testing-deployment.md

@@ -118,9 +118,12 @@ Let's look at the anatomy of the `run packagemanifests` configuration model:
 
 `operator-sdk run bundle-upgrade` assumes OLM is already installed and running on your 
 cluster and that the Operator has a valid [bundle][bundle-format]. It also assumes that 
-the previous version of the Operator was deployed on the cluster using `run bundle` command 
-or traditionally via OLM. See the [CLI overview][doc-cli-overview] for commands to work 
-with an OLM installation and generate a bundle.
+the previous version of the Operator was either deployed on the cluster using `run bundle` 
+command or traditionally via OLM. Another assumption of this command is that the newer operator bundle
+should not exist in the index image, if the previous version of the operator bundle was installed 
+traditionally using OLM. This will cause the registry pod to fail as the bundle is already added to the 
+index that provides package and csv. See the [CLI overview][doc-cli-overview] for commands to work with 
+an OLM installation and generate a bundle.
 
 ```
 operator-sdk run bundle-upgrade <bundle-image> [--kubeconfig=] [--namespace=] [--timeout=]