Rename {-> Max}Combo sort mode

I have a feeling this is going to save asses in an indeterminate future.

osu.Game/Scoring/ScoreInfoExtensions.cs

@@ -44,7 +44,7 @@ namespace osu.Game.Scoring
                 case LeaderboardSortMode.Accuracy:
                     return scores.OrderByDescending(s => s.Accuracy).ThenByDescending(s => s.TotalScore);
 
-                case LeaderboardSortMode.Combo:
+                case LeaderboardSortMode.MaxCombo:
                     return scores.OrderByDescending(s => s.MaxCombo).ThenByDescending(s => s.TotalScore);
 
                 case LeaderboardSortMode.Misses:

osu.Game/Screens/Select/Leaderboards/LeaderboardSortMode.cs

@@ -1,13 +1,18 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System.ComponentModel;
+
 namespace osu.Game.Screens.Select.Leaderboards
 {
     public enum LeaderboardSortMode
     {
         Score,
         Accuracy,
-        Combo,
+
+        [Description("Max Combo")]
+        MaxCombo,
+
         Misses,
         Date,
     }