README: Fix support matrix.

[Gacko]

What this PR does / why we need it:

It fixes the support matrix. Unsupported versions were still emphasized, also I improved the indentation and removed wildcards from where they are not required.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• CVE Report (Scanner found CVE and adding report)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation only

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added unit and/or e2e tests to cover my changes.
• All new and existing tests passed.

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[Gacko]

/triage accepted
/kind documentation
/priority important-soon
/cc @longwuyuan @strongjz

[rikatz]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Gacko, rikatz

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• OWNERS [Gacko,rikatz]

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