Incorrect anchor link for "leaseholder" in architecture terms section

## Summary

In the CockroachDB Architecture Terms section of the docs, the "leaseholder" reference listed under the Raft leader entry contains an incorrect hyperlink anchor. The link currently points to #architecture-raft-leader instead of the correct #leaseholder anchor.

## Steps to Reproduce

1. Navigate to the CockroachDB [Architecture Terms glossary page](https://www.cockroachlabs.com/docs/stable/architecture/glossary#cockroachdb-architecture-terms) in the docs.
2. Locate the [Raft leader entry](https://www.cockroachlabs.com/docs/stable/architecture/glossary#raft-leader).
3. Click the leaseholder hyperlink within that entry.

## Expected Behavior

Clicking the "leaseholder" link should navigate to the `#leaseholder` section of the page.

## Actual Behavior

The link navigates to the `#architecture-raft-leader` anchor instead. Inspecting the element confirms the incorrect `href`:

```html
leaseholder
```

## Proposed Fix

```html
leaseholder
```

Jira issue: DOC-16978