[2654] fix

Based on comments in eclipse-che/che#18514
1. replaced OpenShift with {platforms-name}
in Prerequisites,
2. added the `update` step,
3. rewrote the upgrade step description.

Bug: https://issues.redhat.com/browse/RHDEVDOCS-2654

modules/installation-guide/partials/proc_upgrading-che-using-the-cli-management-tool.adoc

@@ -11,7 +11,7 @@ This section describes how to upgrade from previous minor version using the CLI
 
 * An administrative account on an instance of {platforms-name}.
 
-* A running instance of a previous minor version of {prod}, installed using the CLI management tool on the same instance of OpenShift, in the `__<{prod-namespace}>__` project.
+* A running instance of a previous minor version of {prod}, installed using the CLI management tool on the same instance of {platforms-name}, in the `__<{prod-namespace}>__` project.
 
 * An installation of the `{prod-cli}` {prod-ver} version management tool. See xref:overview:using-the-chectl-management-tool.adoc[].
 
@@ -21,7 +21,12 @@ This section describes how to upgrade from previous minor version using the CLI
 
 . Shut down all workspaces in the {prod-short} {prod-prev-ver} instance.
 
-. Run the following command:
+. Run the following command to make sure your {prod-cli} version is the latest:
+----
+$ {prod-cli} update
+----
+
+. Upgrade {prod-short} with the following command:
 +
 [subs="+attributes,+quotes"]
 ----