Automatic merge from submit-queue (batch tested with PRs 60737, 60739, 61080, 60968, 60951). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Update Kubelet command option description for IPv6

**What this PR does / why we need it**:
The restriction for a /66 cidr was removed in PR #60089.
Removing this reference from the command options description.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #60734

**Special notes for your reviewer**:

**Release note**:

```release-note
NONE
```