`oc explain` output of default overlaySize is outdated

This bug is a backport clone of [Bugzilla Bug 2081119](https://bugzilla.redhat.com/show_bug.cgi?id=2081119). The following is the description of the original bug:
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Description of problem:

`oc explain` output of default overlaySize is 10G. The outdated doc confused the customer with default overlaySize. The description should be updated since the default was removed from the implementation of storage.conf.

Version-Release number of selected component (if applicable):

How reproducible:

Actual results:

$ oc explain containerRuntimeConfig.spec.containerRuntimeConfig.logLevel
KIND: ContainerRuntimeConfig
VERSION: machineconfiguration.openshift.io/v1

FIELD: logLevel <string>

DESCRIPTION:
logLevel specifies the verbosity of the logs based on the level it is set
to. Options are fatal, panic, error, warn, info, and debug.
[qiwan@qiwan ~]$ oc explain containerRuntimeConfig.spec.containerRuntimeConfig.overlaySize
KIND: ContainerRuntimeConfig
VERSION: machineconfiguration.openshift.io/v1

FIELD: overlaySize <string>

DESCRIPTION:
overlaySize specifies the maximum size of a container image. This flag can
be used to set quota on the size of container images. (default: 10GB).

Expected results:

$ oc explain containerRuntimeConfig.spec.containerRuntimeConfig.logLevel
KIND: ContainerRuntimeConfig
VERSION: machineconfiguration.openshift.io/v1

FIELD: logLevel <string>

DESCRIPTION:
logLevel specifies the verbosity of the logs based on the level it is set
to. Options are fatal, panic, error, warn, info, and debug.
[qiwan@qiwan ~]$ oc explain containerRuntimeConfig.spec.containerRuntimeConfig.overlaySize
KIND: ContainerRuntimeConfig
VERSION: machineconfiguration.openshift.io/v1

FIELD: overlaySize <string>

DESCRIPTION:
overlaySize specifies the maximum size of a container image. This flag can
be used to set quota on the size of container images.

Additional info: