Feedback: Batch Delete Expired Data with Row-Level TTL

Page: https://cockroachlabs.com/docs/v24.3/row-level-ttl.html

## What is the reason for your feedback?

Under the `ttl_select_rate_limit` parameter storage description, the term 'leaseholder' is used where 'leaseholder node' would be more appropriate. In my customer's example, they have a table with 8000 ranges (and therefore 8000 leaseholders - as per the definition [here](https://www.cockroachlabs.com/docs/v24.3/architecture/overview#architecture-leaseholder)) but only 6 nodes where leaseholders are placed. The `ttl_select_rate_limit` is calculated based on the number of nodes where leaseholders are placed (e.g. 6) rather than the number of leaseholders for the table (e.g. 8000). This caused confusion for both myself and my customer when we read it, so it would be good if this could be clarified. Thanks!

Jira issue: DOC-12194