add docs on dumping the catalog snapshot (#7689)

* find the versions of the operators in the catalog snapshots

docs/Operator_Catalog_Snapshots.adoc

@@ -21,7 +21,7 @@ There are 4 catalogs in OpenShift (as of July 2020):
 
 An operator catalog snapshot is created by building a container image containing the YAML definitions of a catalog at that particular state in time. Once the catalog image has been built it needs to be hosted in a (public) container registry.
 
-This image should no longer change - even if the online catalogs get updated with newer releases of any given operator. This is achieved by tagging the image with a unique tag. 
+This image should no longer change - even if the online catalogs get updated with newer releases of any given operator. This is achieved by tagging the image with a unique tag.
 
 Once the catalog snapshot image is available a catalog source can be created in OpenShift that points to this particular catalog image thus freezing the available operator versions.
 
@@ -39,6 +39,32 @@ The full process for creating an operator catalog snapshot image is:
 . Wait for the operator to be running.
 . Optional: Create the custom resources for the operator to "do its magic".
 
+== Dumping all the entries from a catalog snapshot image
+
+Prerequisites:
+
+* Install `opm` from https://mirror.openshift.com/pub/openshift-v4/
+* Install `podman`
+
+Procedure:
+
+* Login to the https://quay.io/repository/gpte-devops-automation/olm_snapshot_redhat_catalog?tab=tags&tag=latest[container registry]
+** `podman login quay.io`
+* Browse the WWW to: https://quay.io/repository/gpte-devops-automation/
+* Choose the snapshot image that matches the date you want and the OCP version you want
+** e.g. `v4.14_2024_03_11`
+* Click on the "Fetch Tag" button and use the UI to copy get the image, tag, and digest
+** e.g. `quay.io/gpte-devops-automation/olm_snapshot_redhat_catalog@sha256:664bfd475d0b1e7690c761fd9c59530cee5de830016bb672568867c440aa463f`
+* Run `opm render` to get the YAML definition of the catalog
++
+[source]
+----
+mkdir ~/catalog
+opm render quay.io/gpte-devops-automation/olm_snapshot_redhat_catalog@sha256:664bfd475d0b1e7690c761fd9c59530cee5de830016bb672568867c440aa463f -oyaml > ~/catalog/index.yaml
+----
++
+* Browse the YAML file for `entries` stanzas which might have your desired operators.
+
 == Preparing to create an operator catalog snapshot image
 
 * Determine the catalogs for which you want to create a catalog snapshot image.