docs: Add cluster login step to Open VSX deployment procedures (#3123)

* docs: Add cluster login step to Open VSX deployment procedures

Add explicit cluster login instructions to ensure users are authenticated
before running Open VSX deployment tasks. This clarifies the authentication
prerequisite and prevents common setup errors.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

* Update modules/administration-guide/pages/proc_deploy-open-vsx-from-workspace.adoc

Co-authored-by: Valerii Svydenko <vsvydenk@redhat.com>

---------

Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>
Co-authored-by: Valerii Svydenko <vsvydenk@redhat.com>

Author: 3 people

modules/administration-guide/pages/proc_deploy-open-vsx-from-workspace.adoc

@@ -29,6 +29,9 @@ The link:https://github.com/eclipse-openvsx/openvsx/blob/master/.devfile.yaml[.d
 The environment, including all necessary commands, is defined in the `.devfile.yaml` file.
 ====
 
+. Login to the cluster as a cluster administrator from the workspace terminal:
+.. Navigate to *Terminal* -> *New Terminal*
+.. Execute: `$ oc login --token=<USER_TOKEN> --server=<CLUSTER_API_URL>`
 . Create a new project for Open VSX.
 +
 Run the `2.1. Create Namespace for OpenVSX` task in the workspace:

modules/administration-guide/partials/proc_adding-or-removing-extensions-in-a-workspace.adoc

@@ -13,8 +13,8 @@ The embedded plugin registry is deprecated. Setting up an internal, on-premises
 
 .Prerequisites
 
-* You are logged in to your {prod-short} instance as an administrator.
 * You have started a workspace using the link:{plugin-registry-repo-url}[plugin registry repository].
+* You are logged in to the cluster as a cluster administrator from the workspace terminal: `$ oc login --token=<USER_TOKEN> --server=<CLUSTER_API_URL>`
 * You have created a link:https://access.redhat.com/terms-based-registry/[Red Hat Registry Service Account] and have the username and token available.
 * For IBM Power (`ppc64le`) and IBM Z (`s390x`) architectures, you must build the custom plugin registry locally on the corresponding hardware.
 * (Optional) You can rebuild the container based on the latest tag or SHA to get the latest security fixes after a {prod-short} update.