fix: Fix {{ _doc.title }}

Author: SilverRainZ

src/sphinxnotes/render/utils/ctxproxy.py

@@ -119,6 +119,10 @@ def _top_section(self) -> Section:
         assert section
         return Section(section)
 
+    @proxy_property
+    def title(self) -> Node | None:
+        return self._top_section().title
+
     @proxy_property
     def sections(self) -> tuple[Section, ...]:
         return self._top_section().sections