📖 Fix broken IPAM kustomization links in releasing.md

[peppi-lotta]

What this PR does / why we need it: Change IPAM links to pass link check. These wiles no longer exist in main but are relevant for release branch.

[tuminoid]

/approve
/retitle 📖 Fix broken IPAM kustomization links in releasing.md

[metal3-io-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: tuminoid

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[adilGhaffarDev]

/lgtm
/override metal3-centos-e2e-integration-test-release-1-9

[metal3-io-bot]

@adilGhaffarDev: Overrode contexts on behalf of adilGhaffarDev: metal3-centos-e2e-integration-test-release-1-9

In response to this:

/lgtm
/override metal3-centos-e2e-integration-test-release-1-9

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