Side-by-side manual links to missing `side-by-side-view-1.md`

The side-by-side view manual contains a `config` link to `./side-by-side-view-1.md`:

https://github.com/dandavison/delta/blob/f85c46ba8b913aa3208af0f3573db90286e56e18/manual/src/side-by-side-view.md#L8

No file with that name exists in `manual/src`, so the source-manual link is broken. The generated root README also renders the corresponding link as `#side-by-side-view-1`, but there is no matching anchor.

Suggested fix: remove the `config` link or retarget it to the intended existing configuration section/file.

I searched issues and PRs for the exact missing filename and found no duplicate.

Start with manual/src/side-by-side-view.md and inspect the referenced config link and nearby existing configuration sections in manual/src. Remove or retarget the broken link, then verify that the generated root README no longer contains the unmatched side-by-side-view-1 anchor.

Written by the indexing model from the issue text.