update documentation to include installation with in-cluster prometheus in openshift

[mittal-ishaan]

Related Issue

Proposed Changes

This PR adds the documentation for installing kubecost in openshift clusters without having the bundled prometheus but using the in-cluster prometheus.

Depends upon:

opencost/opencost#2944
kubecost/cost-analyzer-helm-chart#3700

[chipzoller]

Thanks for doing this!

[chipzoller]

Are all comments resolved? If so, please resolve.

[thomasvn]

The drawback to doing this is that now this link will no longer be checked by the CI's link-checker. What happens if we someday decide to rename or delete values-openshift.yaml?

Although referencing develop branch comes with drawbacks, I still think it's more valuable than putting <$VERSION> here. @mittal-ishaan @chipzoller thoughts?

[mittal-ishaan]

We can use develop. But we can also start with having versions. like v2.5 and then update docs when every new minor or major version gets released.

[chipzoller]

@thomasvn, the problem here with listing files from the develop branch is we put users in a precarious and potentially unsupported position when they install a versioned release but use a values file which doesn't correspond to that release. We really need to get away from that practice entirely when we're talking about our official docs. Rather than putting in a placeholder like <$VERSION> we should make this the same as the version referenced by the docs. For example, if users are reading version 2.5 of our docs then any files that are associated with that release should be pointed to the v2.5 branch. This obviously means that any new files that get referenced are "released" in that branch.