[gnome-nibbles] Describe the category type in the scores dialog

[Iulian Radu <iulianradu src gnome org>]

commit 7b1d3b89b678d582533d4f61a27e0d9de958cd29
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sat Sep 19 18:19:47 2015 -0500

    Describe the category type in the scores dialog

 src/gnome-nibbles.vala |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/gnome-nibbles.vala b/src/gnome-nibbles.vala
index eacc0a3..a9792a3 100644
--- a/src/gnome-nibbles.vala
+++ b/src/gnome-nibbles.vala
@@ -553,7 +553,8 @@ public class Nibbles : Gtk.Application
         scorecats.add (new Games.Scores.Category ("fast-fakes", "Fast with Fakes"));
 
         scores_context = new Games.Scores.Context ("gnome-nibbles",
-                                                   "",
+                                                   /* Displayed on the scores dialog, preceeding a 
difficulty. */
+                                                   _("Difficulty Level:"),
                                                    window,
                                                    category_request,
                                                    Games.Scores.Style.PLAIN_DESCENDING);