[gnome-nibbles] Fix a translator comment

[Piotr Drąg <piotrdrag src gnome org>]

commit a6e16f24a66656b1fdae973014555a48c900d58d
Author: Piotr Drąg <piotrdrag gmail com>
Date:   Sat Jan 28 02:12:05 2017 +0100

    Fix a translator comment
    
    They need to be exactly one line above a string to show up in .po files.

 src/preferences-dialog.vala |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/preferences-dialog.vala b/src/preferences-dialog.vala
index 49d4f99..f054a10 100644
--- a/src/preferences-dialog.vala
+++ b/src/preferences-dialog.vala
@@ -222,11 +222,11 @@ private class PreferencesDialog : Gtk.Dialog
             {
                 valid = false;
 
-                /* Translators: This string appears when one tries to assign an already assigned key */
                 var dialog = new Gtk.MessageDialog (window,
                                                     Gtk.DialogFlags.DESTROY_WITH_PARENT,
                                                     Gtk.MessageType.WARNING,
                                                     Gtk.ButtonsType.OK,
+                                                    /* Translators: This string appears when one tries to 
assign an already assigned key */
                                                     _("The key you selected is already assigned!"));
 
                 dialog.run ();