[libgames-support] scores: Add a comment

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 0193fe1ad21c7278666d94abcb12644c05799d6e
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Sat Feb 13 14:11:04 2016 -0600

    scores: Add a comment

 games/scores/context.vala |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/games/scores/context.vala b/games/scores/context.vala
index 370a525..bf776c4 100644
--- a/games/scores/context.vala
+++ b/games/scores/context.vala
@@ -54,7 +54,12 @@ public class Context : Object
         return str_equal (a.name, b.name);
     };
 
-    /* A function provided by the game that converts the category key to a category. */
+    /* A function provided by the game that converts the category key to a
+     * category. Why do we have this, instead of expecting games to pass in a
+     * list of categories? Because some games need to create categories on the
+     * fly, like Mines, which allows for custom board sizes. These games do not
+     * know in advance which categories may be in use.
+     */
     public delegate Category? CategoryRequestFunc (string category_key);
     private CategoryRequestFunc category_request;