OSDOCS-3860: add dns cache tuning

[jldohmann]

Version(s): 4.12+

Issue: https://issues.redhat.com/browse/OSDOCS-3860

Link to docs preview: http://file.rdu.redhat.com/jdohmann/OSDOCS-3860/networking/dns-operator.html#nw-dns-cache-tuning_dns-operator

QE review:

• [ ] QE has approved this change.

Additional information:

[ocpdocs-previewbot]

🤖 Updated build preview is available at: https://51765--docspreview.netlify.app

Build log: https://circleci.com/gh/ocpdocs-previewbot/openshift-docs/2400

[jldohmann]

@brandisher could you PTAL for SME feedback/ack? This is the doc for the CoreDNS tuning feature, NE-757. Thank you!

[jldohmann]

2a52bc8..5fcc470 implement SME feedback 5fcc470..e9f8019 implement peer review feedback e9f80190..10b54a24 rebase before merge

[jldohmann]

@melvinjoseph86 could you PTAL for QE ack? This is the doc for the CoreDNS cache tuning feature, NE-757. Thank you!

[melvinjoseph86]

/label qe-approved

[jldohmann]

/cherrypick enterprise-4.12

[openshift-cherrypick-robot]

@jldohmann: new pull request created: #52115

In response to this:

/cherrypick enterprise-4.12

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