[libadwaita] preferences-group: Correct nullable annotation

[Alexander Mikhaylenko <alexm src gnome org>]

commit 447e3626c05fb771273da209124d5ef086315a79
Author: Maximiliano Sandoval R <msandova protonmail com>
Date:   Mon Apr 4 14:05:30 2022 +0200

    preferences-group: Correct nullable annotation
    
    For header-suffix setter.

 src/adw-preferences-group.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/adw-preferences-group.c b/src/adw-preferences-group.c
index 1c9fd1e4..f273e885 100644
--- a/src/adw-preferences-group.c
+++ b/src/adw-preferences-group.c
@@ -583,7 +583,7 @@ adw_preferences_group_get_header_suffix (AdwPreferencesGroup *self)
 /**
  * adw_preferences_group_set_header_suffix:
  * @self: a `AdwPreferencesGroup`
- * @suffix (nullable): the suffix to set
+ * @suffix: (nullable): the suffix to set
  *
  * Sets the suffix for @self's header.
  *