Update stale docs about OWNERS files

[VannTen]

Should avoid to the next maintainer looking at OWNERS files docs to needlessy avoid filters for use with approvers

/sig contribex

[k8s-ci-robot]

@VannTen: The label(s) sig/contribex cannot be applied, because the repository doesn't have them.

In response to this:

Should avoid to the next maintainer looking at OWNERS files docs to needlessy avoid filters for use with approvers

/sig contribex

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: VannTen
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• contributors/guide/OWNERS

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