fix hide TOC when document has only a single heading

A table of contents is unhelpful when the README contains just one heading (title-only or single section). The TOC now requires at least two body headings before rendering.

Commit
7fe18572ca126e503368e0e0e02f8747ad06a711
Author
Claude Sonnet 4 <claude@anthropic.invalid>
Author date
Committer
Marius Peter <dev@marius-peter.com>
Committer date
lib/doc_format.ml
index e245fbd9..e4654409 100644..100644
@@ -129,7 +129,7 @@
129 129
130 130 let render_toc ~title_text body_headings =
131 131 match body_headings with
132 Removed: | [] -> Ui.nothing
132 Added: | [] | [ _ ] -> Ui.nothing
133 133 | _ ->
134 134 let toc_anchor = new_anchor () in
135 135 (match title_text with Some t -> ignore (toc_anchor t) | None -> ());