Upgrade cluster on ECK doc is not considering Helm based deployments #3591
Description
Our ECK upgrade doc was originally created when ECK didn't offer a helm chart, hence it doesn't mention that if helm charts are used, the procedure would be different.
We consider helm in the operator upgrade document, but not in the cluster upgrades doc.
The helm chart is documented here, and there are multiple options but we don't explain upgrades there either.
We should give guidance to users running ECK with helm charts about how to upgrade deployments, which is very straight forward.
This has been discovered while working on #3398