[libnotify] notification: Document get_activation_token argument

[Marco Trevisan <marcotrevi src gnome org>]

commit 9d28fa36008fc820bd9449737f081cec551c2810
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Tue Jun 7 03:06:18 2022 +0200

    notification: Document get_activation_token argument

 libnotify/notification.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/libnotify/notification.c b/libnotify/notification.c
index 18d7203..0276df5 100644
--- a/libnotify/notification.c
+++ b/libnotify/notification.c
@@ -1385,6 +1385,7 @@ notify_notification_add_action (NotifyNotification  *notification,
 
 /**
  * notify_notification_get_activation_token:
+ * @notification: The notification.
  *
  * If an an action is currently being activated, return the activation token.
  * This function is intended to be used in a #NotifyActionCallback to get