[gtk+/gtk-3-20] Add a comment to explain numbers here

[Matthias Clasen <matthiasc src gnome org>]

commit a2a369ae1c9b393297fed6bbdb181a9189714e62
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Apr 19 07:34:44 2016 -0400

    Add a comment to explain numbers here
    
    This explains the change in the previous commit.

 modules/printbackends/cups/gtkprintbackendcups.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/modules/printbackends/cups/gtkprintbackendcups.c 
b/modules/printbackends/cups/gtkprintbackendcups.c
index 2d63ad4..d114076 100644
--- a/modules/printbackends/cups/gtkprintbackendcups.c
+++ b/modules/printbackends/cups/gtkprintbackendcups.c
@@ -2494,6 +2494,7 @@ get_reason_msg_desc (guint i,
 {
   gchar *reason_msg_desc;
 
+  /* The numbers must match the indices in the printer_messages array */
   switch (i)
     {
       case 0: