Added information related to root-partition-auto-resize (backport #1262)

[mergify]

This is an automatic backport of pull request #1262 done by Mergify.
Cherry-pick of 09511c5 has failed:

On branch mergify/bp/master/pr-1262
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	both modified:   docs/configuration/system/option.rst

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To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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