General cleanups.

osu.Game.Rulesets.Mania/Timing/TimeRelativeContainer.cs

@@ -129,6 +129,11 @@ namespace osu.Game.Rulesets.Mania.Timing
                 base.Add(drawable);
             }
 
+            /// <summary>
+            /// Whether this timing section can contain a drawable. A timing section can contain a drawable if the drawable
+            /// can be placed within the timing section's bounds (in this case, from the start of the timing section up to infinity).
+            /// </summary>
+            /// <param name="drawable">The drawable to check.</param>
             public bool CanContain(Drawable drawable) => content.Y >= drawable.Y;
         }
     }

osu.Game.Rulesets.Mania/Timing/TimingSection.cs

@@ -5,11 +5,26 @@ using osu.Game.Beatmaps.Timing;
 
 namespace osu.Game.Rulesets.Mania.Timing
 {
+    /// <summary>
+    /// A point in the map where the beat length or speed multiplier has changed .
+    /// </summary>
     public class TimingSection
     {
+        /// <summary>
+        /// The time at which the change occurred.
+        /// </summary>
         public double StartTime;
+        /// <summary>
+        /// The duration of this timing section - lasts until the next timing section.
+        /// </summary>
         public double Duration;
+        /// <summary>
+        /// The beat length, includes any speed multiplier.
+        /// </summary>
         public double BeatLength;
+        /// <summary>
+        /// The time signature of this timing section.
+        /// </summary>
         public TimeSignatures TimeSignature;
     }
 }

osu.Game.Rulesets.Mania/UI/ManiaPlayfield.cs

@@ -96,7 +96,7 @@ namespace osu.Game.Rulesets.Mania.UI
                         },
                         barlineContainer = new TimeRelativeContainer(timingSections)
                         {
-                            Name = "Barlines",
+                            Name = "Bar lines",
                             Anchor = Anchor.BottomCentre,
                             Origin = Anchor.BottomCentre,
                             RelativeSizeAxes = Axes.Both,