chore(docs): update doc/config.md to reflect 3.0 changes (backport #922)

[mergify[bot]]

Welcome to Cryostat! 👋

Before contributing, make sure you have:

• [x] Read the contributing guidelines
• [x] Linked a relevant issue which this PR resolves
• [x] Linked any other relevant issues, PR's, or documentation, if any
• [x] Resolved all conflicts, if any
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Fixes: #899

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This is an automatic backport of pull request #922 done by Mergify.

[mergify[bot]]

Cherry-pick of 56bfead1943a010162479e5493b8100f9f8cb3d9 has failed:

On branch mergify/bp/cryostat-v3.0/pr-922
Your branch is up to date with 'origin/cryostat-v3.0'.

You are currently cherry-picking commit 56bfead.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
    modified:   Makefile
    modified:   docs/config.md
    modified:   internal/controllers/suite_test.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
    both modified:   bundle/manifests/cryostat-operator.clusterserviceversion.yaml

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally