[empathy] add translators comment explaining the insufficient balance error (#649735)

[Guillaume Desmottes <gdesmott src gnome org>]

commit 514c6109204c180fa7fc79581058f6dc8156a99e
Author: Guillaume Desmottes <guillaume desmottes collabora co uk>
Date:   Mon May 9 10:18:41 2011 +0200

    add translators comment explaining the insufficient balance error (#649735)

 libempathy-gtk/empathy-chat.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/libempathy-gtk/empathy-chat.c b/libempathy-gtk/empathy-chat.c
index 3e8a9c7..b580812 100644
--- a/libempathy-gtk/empathy-chat.c
+++ b/libempathy-gtk/empathy-chat.c
@@ -1294,6 +1294,8 @@ chat_send_error_cb (EmpathyTpChat          *tp_chat,
 	gchar       *str;
 
 	if (!tp_strdiff (dbus_error, TP_ERROR_STR_INSUFFICIENT_BALANCE)) {
+		/* translators: error used when user doesn't have enough credit on his
+		 * account to send the message. */
 		error = _("insufficient balance to send message");
 	} else if (!tp_strdiff (dbus_error, TP_ERROR_STR_NOT_CAPABLE)) {
 		error = _("not capable");