📖 Fix version support matrix

[fabriziopandini]

What this PR does / why we need it:
Fix version support matrix after 1.10 release (+ amend wrong EOL dates for old releases)

/area documentation
/cherry-pick release-1.10

[fabriziopandini]

/cherry-pick release-1.10

[k8s-infra-cherrypick-robot]

@fabriziopandini: once the present PR merges, I will cherry-pick it on top of release-1.10 in a new PR and assign it to you.

In response to this:

/cherry-pick release-1.10

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[mboersma]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 773c6999758665000778db6d662c0fdc8e4eac6c

[fabriziopandini]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: fabriziopandini

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[k8s-infra-cherrypick-robot]

@fabriziopandini: new pull request created: #12124

In response to this:

/cherry-pick release-1.10

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.