[Feedback]: Disk Usage API missing response

### Was the documentation helpful?

No

### What documentation page is affected

https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-indices-disk-usage

old: 
https://www.elastic.co/guide/en/elasticsearch/reference/8.18/indices-disk-usage.html contains the response and a little bit of explanation

### Description

see above