[gnome-builder] transfers: fix typo

[Matthew Leeds <mwleeds src gnome org>]

commit 9560b62398ffd007c2aba3bf4a257441b047a799
Author: Matthew Leeds <mleeds redhat com>
Date:   Sat Feb 18 23:24:45 2017 -0600

    transfers: fix typo

 libide/transfers/ide-transfer-manager.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/libide/transfers/ide-transfer-manager.c b/libide/transfers/ide-transfer-manager.c
index 0a6585c..76739e5 100644
--- a/libide/transfers/ide-transfer-manager.c
+++ b/libide/transfers/ide-transfer-manager.c
@@ -382,7 +382,7 @@ notify_properties:
  * ide_transfer_manager_execute_async:
  * @self: An #IdeTransferManager
  * @cancellable: (nullable): A #GCancellable
- * @callback: (nullable) A callback or %NULL
+ * @callback: (nullable): A callback or %NULL
  * @user_data: user data for @callback
  *
  * This is a convenience function that will queue @transfer into the transfer