Add XMLDocs to difficulty attribute properties

osu.Game.Rulesets.Catch/Difficulty/CatchDifficultyAttributes.cs

@@ -9,6 +9,12 @@ namespace osu.Game.Rulesets.Catch.Difficulty
 {
     public class CatchDifficultyAttributes : DifficultyAttributes
     {
+        /// <summary>
+        /// The perceived approach rate inclusive of rate-adjusting mods (DT/HT/etc).
+        /// </summary>
+        /// <remarks>
+        /// Rate-adjusting mods don't directly affect the approach rate difficulty value, but have a perceived effect as a result of adjusting audio timing.
+        /// </remarks>
         [JsonProperty("approach_rate")]
         public double ApproachRate { get; set; }
 

osu.Game.Rulesets.Mania/Difficulty/ManiaDifficultyAttributes.cs

@@ -9,9 +9,18 @@ namespace osu.Game.Rulesets.Mania.Difficulty
 {
     public class ManiaDifficultyAttributes : DifficultyAttributes
     {
+        /// <summary>
+        /// The perceived hit window for a GREAT hit inclusive of rate-adjusting mods (DT/HT/etc).
+        /// </summary>
+        /// <remarks>
+        /// Rate-adjusting mods don't directly affect the hit window, but have a perceived effect as a result of adjusting audio timing.
+        /// </remarks>
         [JsonProperty("great_hit_window")]
         public double GreatHitWindow { get; set; }
 
+        /// <summary>
+        /// The score multiplier applied via score-reducing mods.
+        /// </summary>
         [JsonProperty("score_multiplier")]
         public double ScoreMultiplier { get; set; }
 

osu.Game.Rulesets.Osu/Difficulty/OsuDifficultyAttributes.cs

@@ -12,30 +12,68 @@ namespace osu.Game.Rulesets.Osu.Difficulty
 {
     public class OsuDifficultyAttributes : DifficultyAttributes
     {
+        /// <summary>
+        /// The difficulty corresponding to the aim skill.
+        /// </summary>
         [JsonProperty("aim_difficulty")]
         public double AimDifficulty { get; set; }
 
+        /// <summary>
+        /// The difficulty corresponding to the speed skill.
+        /// </summary>
         [JsonProperty("speed_difficulty")]
         public double SpeedDifficulty { get; set; }
 
+        /// <summary>
+        /// The difficulty corresponding to the flashlight skill.
+        /// </summary>
         [JsonProperty("flashlight_difficulty")]
         public double FlashlightDifficulty { get; set; }
 
+        /// <summary>
+        /// Describes how much of <see cref="AimDifficulty"/> is contributed to by hitcircles or sliders.
+        /// A value closer to 1.0 indicates most of <see cref="AimDifficulty"/> is contributed by hitcircles.
+        /// A value closer to 0.0 indicates most of <see cref="AimDifficulty"/> is contributed by sliders.
+        /// </summary>
         [JsonProperty("slider_factor")]
         public double SliderFactor { get; set; }
 
+        /// <summary>
+        /// The perceived approach rate inclusive of rate-adjusting mods (DT/HT/etc).
+        /// </summary>
+        /// <remarks>
+        /// Rate-adjusting mods don't directly affect the approach rate difficulty value, but have a perceived effect as a result of adjusting audio timing.
+        /// </remarks>
         [JsonProperty("approach_rate")]
         public double ApproachRate { get; set; }
 
+        /// <summary>
+        /// The perceived overall difficulty inclusive of rate-adjusting mods (DT/HT/etc).
+        /// </summary>
+        /// <remarks>
+        /// Rate-adjusting mods don't directly affect the overall difficulty value, but have a perceived effect as a result of adjusting audio timing.
+        /// </remarks>
         [JsonProperty("overall_difficulty")]
         public double OverallDifficulty { get; set; }
 
+        /// <summary>
+        /// The beatmap's drain rate. This doesn't scale with rate-adjusting mods.
+        /// </summary>
         public double DrainRate { get; set; }
 
+        /// <summary>
+        /// The number of hitcircles in the beatmap.
+        /// </summary>
         public int HitCircleCount { get; set; }
 
+        /// <summary>
+        /// The number of sliders in the beatmap.
+        /// </summary>
         public int SliderCount { get; set; }
 
+        /// <summary>
+        /// The number of spinners in the beatmap.
+        /// </summary>
         public int SpinnerCount { get; set; }
 
         public override IEnumerable<(int attributeId, object value)> ToDatabaseAttributes()

osu.Game.Rulesets.Taiko/Difficulty/TaikoDifficultyAttributes.cs

@@ -9,18 +9,39 @@ namespace osu.Game.Rulesets.Taiko.Difficulty
 {
     public class TaikoDifficultyAttributes : DifficultyAttributes
     {
+        /// <summary>
+        /// The difficulty corresponding to the stamina skill.
+        /// </summary>
         [JsonProperty("stamina_difficulty")]
         public double StaminaDifficulty { get; set; }
 
+        /// <summary>
+        /// The difficulty corresponding to the rhythm skill.
+        /// </summary>
         [JsonProperty("rhythm_difficulty")]
         public double RhythmDifficulty { get; set; }
 
+        /// <summary>
+        /// The difficulty corresponding to the colour skill.
+        /// </summary>
         [JsonProperty("colour_difficulty")]
         public double ColourDifficulty { get; set; }
 
+        /// <summary>
+        /// The perceived approach rate inclusive of rate-adjusting mods (DT/HT/etc).
+        /// </summary>
+        /// <remarks>
+        /// Rate-adjusting mods don't directly affect the approach rate difficulty value, but have a perceived effect as a result of adjusting audio timing.
+        /// </remarks>
         [JsonProperty("approach_rate")]
         public double ApproachRate { get; set; }
 
+        /// <summary>
+        /// The perceived hit window for a GREAT hit inclusive of rate-adjusting mods (DT/HT/etc).
+        /// </summary>
+        /// <remarks>
+        /// Rate-adjusting mods don't directly affect the hit window, but have a perceived effect as a result of adjusting audio timing.
+        /// </remarks>
         [JsonProperty("great_hit_window")]
         public double GreatHitWindow { get; set; }
 

osu.Game/Rulesets/Difficulty/DifficultyAttributes.cs

@@ -31,7 +31,7 @@ namespace osu.Game.Rulesets.Difficulty
         public Mod[] Mods { get; set; }
 
         /// <summary>
-        /// The combined star rating of all skill.
+        /// The combined star rating of all skills.
         /// </summary>
         [JsonProperty("star_rating", Order = -3)]
         public double StarRating { get; set; }