If you carefully read the sentence before your quote, it says, "
For certain sensitive information, Apple uses end-to-end encryption." (Emphasis added.) Then scroll down to the "End-to-end encrypted data" section where it lists the data that is actually end-to-end encrypted. iCloud Backups are not listed there.
AFAIK iCloud backups are not end-to-end encrypted. I believe this past February Tim Cook, or someone else at Apple, was indicating that they were working on changing that. (It was coming up because everyone was wishing the San Bernardino shooter's phone had been backing up to iCloud, so they wouldn't need to get in the phone, they could just access the iCloud backups—IIRC.)