Returns the number of achievements/statistics to display in a category.
Returns the number of achievements/statistics to display in a category. Note this function does not return the total number of achievements in a category; it only returns the number to be displayed in the default UI. Achievements may belong to a category but not be counted for display: e.g. among those which are part of a series (100 Quests Completed, 500 Quests Completed), only the achievement most recently completed and the achievement following it in the series are shown.