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

[m-novotny]

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

delta/manual/src/side-by-side-view.md

Line 8 in f85c46b

By default, side-by-side view has line-numbers activated, and has syntax highlighting in both the left and right panels: [[config](./side-by-side-view-1.md)]

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.