[release-1.6] RHIDP-7175: OCI Image content update (#1196)

* Added content

* Incorporated Armel's comments

* Incorporated Armel's comments

* Minor change

* More refinement

---------

Co-authored-by: Priyanka Abel <[email protected]>

Author: openshift-cherrypick-robot

modules/dynamic-plugins/proc-load-plugin-oci-image.adoc

@@ -7,10 +7,33 @@
 For more information about packaging a third-party plugin, see xref:assembly-package-publish-third-party-dynamic-plugin[].
 
 .Procedure
+. To retrieve plugins from an authenticated registry, complete the following steps:
+.. Log in to the container image registry.
++
+[source,yaml]
+----
+podman login <registry>
+----
+.. Verify the content of the `auth.json` file created after the login.
++
+[source,yaml]
+----
+cat ${XDG_RUNTIME_DIR:-~/.config}/containers/auth.json
+----
+.. Create a secret file using the following example:
++
+[source,yaml]
+----
+oc create secret generic _<secret_name>_ --from-file=auth.json=${XDG_RUNTIME_DIR:-~/.config}/containers/auth.json <1>
+----
++
+** For an Operator-based deployment, replace _<secret_name>_ with `dynamic-plugins-registry-auth`.
+** For a Helm-based deployment, replace _<secret_name>_ with `<Helm_release_name>_-dynamic-plugins-registry-auth`.
+
 . Define the plugin with the `oci://` prefix in the following format in `dynamic-plugins.yaml` file:
 +
 --
-`oci://<image-name>:<tag>!<plugin-name>`
+`oci://_<image_name>_:<tag>!_<plugin_name>_`
 
 .Example configuration in `dynamic-plugins.yaml` file
 [source,yaml]
@@ -20,10 +43,7 @@ plugins:
     package: oci://quay.io/example/image:v0.0.1!backstage-plugin-myplugin
 ----
 --
-
-. Configure authentication for private registries by setting the `REGISTRY_AUTH_FILE` environment variable to the path of the registry configuration file. For example, `~/.config/containers/auth.json` or `~/.docker/config.json`.
-
-. To perform an integrity check, use the image digest in place of the tag in the `dynamic-plugins.yaml` file as follows:
+. To perform an integrity check, use the image digest in place of the tag in the `dynamic-plugins.yaml` file as shown in the following example:
 +
 --
 .Example configuration in `dynamic-plugins.yaml` file
@@ -34,5 +54,4 @@ plugins:
     package: oci://quay.io/example/image@sha256:28036abec4dffc714394e4ee433f16a59493db8017795049c831be41c02eb5dc!backstage-plugin-myplugin
 ----
 --
-
 . To apply the changes, restart the {product-very-short} application.