[gimp] Document that gimp_run_procedure* on error return a string.

[Ed J <edj src gnome org>]

commit 9dfc4eb6a20e6b16ab6e77c48ba3fbcacde4c2a9
Author: Ed J <edj src gnome org>
Date:   Sat May 3 00:12:58 2014 +0100

    Document that gimp_run_procedure* on error return a string.

 libgimp/gimp.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/libgimp/gimp.c b/libgimp/gimp.c
index 083d0f9..d46e5da 100644
--- a/libgimp/gimp.c
+++ b/libgimp/gimp.c
@@ -763,7 +763,9 @@ gimp_uninstall_temp_proc (const gchar *name)
  * passes them to gimp_run_procedure2(). Please look there for further
  * information.
  *
- * Return value: the procedure's return values.
+ * Return value: the procedure's return values unless there was an error,
+ * in which case the zero-th return value will be the error status, and
+ * the first return value will be a string detailing the error.
  **/
 GimpParam *
 gimp_run_procedure (const gchar *name,
@@ -989,7 +991,9 @@ gimp_read_expect_msg (GimpWireMessage *msg,
  * As soon as you don't need the return values any longer, you should
  * free them using gimp_destroy_params().
  *
- * Return value: the procedure's return values.
+ * Return value: the procedure's return values unless there was an error,
+ * in which case the zero-th return value will be the error status, and
+ * the first return value will be a string detailing the error.
  **/
 GimpParam *
 gimp_run_procedure2 (const gchar     *name,