[glib] gdbusconnection: Add missing (nullable) to get_peer_credentials()

[Philip Withnall <pwithnall src gnome org>]

commit ac05ad55fadaac7cdce38f0ea19b2628a9864068
Author: Philip Withnall <philip withnall collabora co uk>
Date:   Tue Oct 6 07:59:19 2015 +0100

    gdbusconnection: Add missing (nullable) to get_peer_credentials()
    
    Since Colin mentioned it on gir-devel-list.

 gio/gdbusconnection.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gio/gdbusconnection.c b/gio/gdbusconnection.c
index c0972ee..b355340 100644
--- a/gio/gdbusconnection.c
+++ b/gio/gdbusconnection.c
@@ -3034,8 +3034,8 @@ g_dbus_connection_get_unique_name (GDBusConnection *connection)
  * each application is a client. So this method will always return
  * %NULL for message bus clients.
  *
- * Returns: (transfer none): a #GCredentials or %NULL if not available.
- *     Do not free this object, it is owned by @connection.
+ * Returns: (transfer none) (nullable): a #GCredentials or %NULL if not
+ *     available. Do not free this object, it is owned by @connection.
  *
  * Since: 2.26
  */