Added the table for clusters and methods for upgrade

[ranjinimn]

#829

I have created the table as per the description provided.

For downstream clusters, we have (at least) 3 different scenarios, and each of them involve different upgrade procedures/mechanisms. AFAIK:

For EIB provisioned clusters -> Fleet approach
For Metal3 provisioned clusters -> Redeploy with a fresh image
For phone-home provisioned clusters -> K8s upgrade via rancher + SUC for the OS and everything else
It would be nice to have a table/matrix/something to explicitly clarify each scenario.

[ranjinimn]

@hardys and @e-minguez I created the table based on the information provided.
One question I had was regarding the inclusion of the "Upgrade controller" in this table? Is there any specific cluster for which we need to use this? Or is this generic?

[e-minguez]

@hardys and @e-minguez I created the table based on the information provided. One question I had was regarding the inclusion of the "Upgrade controller" in this table? Is there any specific cluster for which we need to use this? Or is this generic?

https://documentation.suse.com/suse-edge/3.4/html/edge/components-upgrade-controller.html#components-upgrade-controller-known-issues

Downstream cluster upgrades are not yet managed by the Upgrade Controller.

Also

Currently the Upgrade Controller supports non air-gapped environment upgrades only. Air-gapped upgrades are not
yet possible.

[ranjinimn]

@e-minguez Okay. I will also wait for @hardys inputs on this before I make any changes.
Does that table look okay?

[hardys]

lgtm but looks like the branch needs a rebase?