[gtk/ebassi/gidocgen: 321/500] popovermenubar: Use markdown for css tree

[Emmanuele Bassi <ebassi src gnome org>]

commit b4ad1fa44f3339b44d091c70e905f595d01d8eeb
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Feb 27 20:04:19 2021 -0500

    popovermenubar: Use markdown for css tree

 gtk/gtkpopovermenubar.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkpopovermenubar.c b/gtk/gtkpopovermenubar.c
index 1dd1497e4c..4c5088c734 100644
--- a/gtk/gtkpopovermenubar.c
+++ b/gtk/gtkpopovermenubar.c
@@ -31,13 +31,13 @@
  *
  * # CSS nodes
  *
- * |[<!-- language="plain" -->
+ * ```
  * menubar
  * ├── item[.active]
  * ┊   ╰── popover
  * ╰── item
  *     ╰── popover
- * ]|
+ * ```
  *
  * `GtkPopoverMenuBar` has a single CSS node with name menubar, below which
  * each item has its CSS node, and below that the corresponding popover.