🌱 Update links in release docs

[lentzi90]

What this PR does / why we need it:

Some of the links were still pointing to the old k8s.gcr.io related config, instead of registry.k8s.io.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

1. Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

TODOs:

• squashed commits
• if necessary:
  • includes documentation
  • adds unit tests

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lentzi90

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[lentzi90]

/test pull-cluster-api-provider-openstack-e2e-test

[EmilienM]

/lgtm

[lentzi90]

/test pull-cluster-api-provider-openstack-e2e-test
Please... I'm just changing docs...