🐛 fix(toctree): use section node when title is empty

When :title: was set to empty, a paragraph node was used as the
container instead of a section. Child group headings weren't recognized
by toctree since they weren't inside a proper section hierarchy.

Fixes #48

Author: gaborbernat

src/sphinx_argparse_cli/_logic.py

@@ -187,7 +187,7 @@ def run(self) -> list[Node]:
         self.env.note_reread()  # this document needs to be always updated
         title_text = self.options.get("title", f"{self.parser.prog} - CLI interface").strip()
         if not title_text:
-            home_section: Element = paragraph()
+            home_section: Element = section("")
         else:
             home_section = section("", title("", Text(title_text)), ids=[self.make_id(title_text)], names=[title_text])