[gnome-control-center] Add translator comments to some strings

[Matthias Clasen <matthiasc src gnome org>]

commit 5c4872d77c33eebb88b60ce754fcf45242b6d522
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Apr 3 18:58:53 2013 -0400

    Add translator comments to some strings
    
    Explain what Alternative Character Key and Compose Key are,
    to increase the chances of meaningful translation.
    https://bugzilla.gnome.org/show_bug.cgi?id=697213

 panels/keyboard/cc-keyboard-option.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/panels/keyboard/cc-keyboard-option.c b/panels/keyboard/cc-keyboard-option.c
index 38f3532..a4a8e53 100644
--- a/panels/keyboard/cc-keyboard-option.c
+++ b/panels/keyboard/cc-keyboard-option.c
@@ -359,11 +359,19 @@ cc_keyboard_option_get_all (void)
   objects_list = g_list_prepend (objects_list,
                                  g_object_new (CC_TYPE_KEYBOARD_OPTION,
                                                "group", XKB_OPTION_GROUP_LVL3,
+                                               /* Translators: This key is also known as 'third level
+                                                * chooser'. AltGr is often used for this purpose. See
+                                                * 
https://live.gnome.org/Design/SystemSettings/RegionAndLanguage
+                                                */
                                                "description", _("Alternative Characters Key"),
                                                NULL));
   objects_list = g_list_prepend (objects_list,
                                  g_object_new (CC_TYPE_KEYBOARD_OPTION,
                                                "group", XKB_OPTION_GROUP_COMP,
+                                              /* Translators: The Compose key is used to initiate key
+                                               * sequences that are combined to form a single character.
+                                               * See http://en.wikipedia.org/wiki/Compose_key
+                                               */
                                                "description", _("Compose Key"),
                                                NULL));