Automatic merge from submit-queue (batch tested with PRs 55757, 55741, 55817, 55834, 51530). 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>.
Clarify ExternalNames are hostnames
Updates the documentation for ExternalName to clarify
that they adhere RFC-1123 hostname and are not DNS names.
Fixes#52266
**Release note**:
```release-note
```
7910099e91