[gtk/matthiasc/for-master] fontbutton: Correct the css docs

[Matthias Clasen <matthiasc src gnome org>]

commit 4f0c920a8e5f2ff17b3e8e41f241c13745e5ff6a
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Dec 23 08:57:04 2020 -0500

    fontbutton: Correct the css docs
    
    Mention the wrapper fontbutton node.

 gtk/gtkfontbutton.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtkfontbutton.c b/gtk/gtkfontbutton.c
index dc842eb737..50f86feb54 100644
--- a/gtk/gtkfontbutton.c
+++ b/gtk/gtkfontbutton.c
@@ -59,7 +59,14 @@
  *
  * # CSS nodes
  *
- * GtkFontButton has a single CSS node with name fontbutton.
+ * |[<!-- language="plain" -->
+ * fontbutton
+ * ╰── button.font
+ *     ╰── [content]
+ *]|
+ *
+ * GtkFontButton has a single CSS node with name fontbutton which
+ * contains a button node with the .font style class.
  */
 
 typedef struct _GtkFontButtonClass   GtkFontButtonClass;