[gtk+] printsettings: Add missing docs for output constants

[Matthias Clasen <matthiasc src gnome org>]

commit 0c19be899d163add2258fa488857f4b7de28deb4
Author: Arnel A. Borja <arnelborja src gnome org>
Date:   Mon Aug 26 17:52:59 2013 +0800

    printsettings: Add missing docs for output constants
    
    GTK_PRINT_SETTINGS_OUTPUT_DIR and GTK_PRINT_SETTINGS_OUTPUT_BASENAME
    doesn't have documentation.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=706802

 gtk/gtkprintsettings.h |   19 +++++++++++++++++++
 1 files changed, 19 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkprintsettings.h b/gtk/gtkprintsettings.h
index 05d6f2d..2760e98 100644
--- a/gtk/gtkprintsettings.h
+++ b/gtk/gtkprintsettings.h
@@ -158,7 +158,26 @@ void              gtk_print_settings_set_int                 (GtkPrintSettings
 #define GTK_PRINT_SETTINGS_RESOLUTION_X     "resolution-x"
 #define GTK_PRINT_SETTINGS_RESOLUTION_Y     "resolution-y"
 #define GTK_PRINT_SETTINGS_PRINTER_LPI      "printer-lpi"
+
+/**
+ * GTK_PRINT_SETTINGS_OUTPUT_DIR:
+ *
+ * The key used by the "Print to file" printer to store the
+ * directory to which the output should be written.
+ *
+ * Since: 3.6
+ */
 #define GTK_PRINT_SETTINGS_OUTPUT_DIR       "output-dir"
+
+/**
+ * GTK_PRINT_SETTINGS_OUTPUT_BASENAME:
+ *
+ * The key used by the "Print to file" printer to store the file
+ * name of the output without the path to the directory and the
+ * file extension.
+ *
+ * Since: 3.6
+ */
 #define GTK_PRINT_SETTINGS_OUTPUT_BASENAME  "output-basename"
 
 /**