"Day 2" related documentation changes and improvements for 3.1.1

[ipetrov117]

PR includes:

• Spelling, fixes and improvements overall the flow of the "Day 2" downstream cluster documentation
• Version reference bumps from 3.1.0 -> 3.1.1
• Inclusion to important notes for OS, K8s and Helm upgrades
• Changes incorporating the naming standardisation changes coming from #37

[hardys]

@ipetrov117 looks good to me, but please could we split this into 2 PRs - I think we can merge/backport the general fixes now, but we'll want to wait for the fleet-examples release and other related 3.1.1 changes before we merge that part?

[ipetrov117]

@ipetrov117 looks good to me, but please could we split this into 2 PRs - I think we can merge/backport the general fixes now, but we'll want to wait for the fleet-examples release and other related 3.1.1 changes before we merge that part?

@hardys, to be honest I would prefer to keep this PR as it is and not split it. The improvements are not critical and we can easily add them along side the 3.1.1 changes. Furthermore some improvements rely on the 3.1.1 changes, so the splitting of the PR would not be that easy (main reason why I decided to keep it as a single PR). I suggest merging/discussing #35 and after it is resolved, merging this PR as it is to main. Regarding the cherry-pick for 3.1, we can wait for the fleet-examples release (although previously we have never done that), check the links work on the main branch and transfer the doc to 3.1. The links "should" work (famous last words), as they are just tag bumps from release-3.1.0 to release-3.1.1.

That said I am not opposed to splitting the PR, it just seems like needless work for something that will only land in 3.1.1. I do not see the need to rush this doc fixes before the 3.1.1 related documentation additions, but if you feel like this is the better approach I a have no objections on doing it. Lemme know what you think.

[ipetrov117]

As discussed offline, to avoid any accidental publications of the documentation before the 3.1.1 release, this PR will remain open until the release date comes closer.