OSDOCS#5665: Adding steps to migrate clusters to multi-arch cli

[obrown1205]

Adding documentation to support https://issues.redhat.com/browse/OTA-653.

Version(s):
4.13+

Issue:
https://issues.redhat.com/browse/OSDOCS-5665

Link to docs preview:
https://58104--docspreview.netlify.app/openshift-enterprise/latest/updating/migrating-to-multi-payload.html

QE review:

• QE has approved this change.

Additional information:

[ocpdocs-previewbot]

🤖 Updated build preview is available at:
https://58104--docspreview.netlify.app

Build log: https://circleci.com/gh/ocpdocs-previewbot/openshift-docs/14152

[petr-muller]

/cc

[shellyyang1989]

cc @aleskandro for review from multi-arch side. Thank you!

[evakhoni]

few important notes:

1. before the transition one must verify RetrievedUpdates=True in cvo conditions, otherwise the command will not progress (like I've mentioned in OCPBUGS-8252)
2. probably worth mentioning to update the oc client to the same version as the server in prerequisites, otherwise one may have an older oc with no support for --to-multi-arch
3. worth mentioning that the transition is one-way (i.e. once a cluster is transitioned to multi arch, it can no longer return back to single, neither can accept a non-multi-arch upgrade payload. with that said, AFAIK we're encouraging the customers to transition, so we may want to choice a language that won't scare them away

[kelbrown20]

Adding some stuff with multi-arch in mind. Looks great!

[obrown1205]

/label peer-review-needed

[shellyyang1989]

/label qe-approved

[LalatenduMohanty]

/lgtm

[evakhoni]

sorry for bikeshedding, but since we already ask for Your {product-title} version is up to date to at least version 4.13.0.
and to have You have installed the OpenShift CLI ('oc') that matches the version for your current cluster.
mentioning Your 'oc' client is updated to at least verion 4.13.0. may be redundant

[evakhoni]

as far as the command is concerned, if what we're after is not to expose too much cvo internals, we may as well only ask the user to check oc adm upgrade out, verifying there's no "RetrievedUpates=False" in the output, and if there is, to address it following the message prior to progressing any further. we may as well suggest ignoring "Upgradeable=False", which (overrides aside) should not interfere with the procedure. imho, a lack of RetrievedUpates=False in the output should be good enough to assume RetrievedUpates=True

[evakhoni]

all in all, this doc looks good to me. you can address my two comments above, or can ignore them as well since none of them is a deal breaker in any sense :)

[skrthomas]

merge review lgtm

[skrthomas]

/cherrypick enterprise-4.13

[openshift-cherrypick-robot]

@skrthomas: new pull request created: #58798

In response to this:

/cherrypick enterprise-4.13

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