[gnome-online-accounts/wip/mschraal/goaclient-manager-api-doc] goa: Correct goa_client_get_manager API docs

[Marinus Schraal <mschraal src gnome org>]

commit 7ba7e60526f2737beee6274290d30dd8c8c904b8
Author: Marinus Schraal <mschraal gnome org>
Date:   Tue Sep 1 10:20:14 2020 +0200

    goa: Correct goa_client_get_manager API docs
    
    Closes: #139

 src/goa/goaclient.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/goa/goaclient.c b/src/goa/goaclient.c
index afec7104..ce5729ef 100644
--- a/src/goa/goaclient.c
+++ b/src/goa/goaclient.c
@@ -405,8 +405,8 @@ goa_client_get_object_manager (GoaClient        *self)
  *
  * Gets the #GoaManager for @self.
  *
- * Returns: (transfer none): A #GoaManager. Do not free, the returned
- * object belongs to @self.
+ * Returns: (transfer none) (allow-none): A #GoaManager or %NULL. Do
+ * not free, the returned object belongs to @self.
  */
 GoaManager *
 goa_client_get_manager (GoaClient *self)