Add XML docs for entire model

src/DotTiled/Model/Layers/ImageLayer.cs

@@ -1,13 +1,32 @@
 namespace DotTiled.Model;
 
+/// <summary>
+/// Represents an image layer in a map.
+/// </summary>
 public class ImageLayer : BaseLayer
 {
-  // Attributes
+  /// <summary>
+  /// The X position of the image layer in pixels.
+  /// </summary>
   public uint X { get; set; } = 0;
+
+  /// <summary>
+  /// The Y position of the image layer in pixels.
+  /// </summary>
   public uint Y { get; set; } = 0;
+
+  /// <summary>
+  /// Whether the image drawn by this layer is repeated along the X axis.
+  /// </summary>
   public bool RepeatX { get; set; } = false;
+
+  /// <summary>
+  /// Whether the image drawn by this layer is repeated along the Y axis.
+  /// </summary>
   public bool RepeatY { get; set; } = false;
 
-  // At most one of
+  /// <summary>
+  /// The image to be drawn by this image layer.
+  /// </summary>
   public Image? Image { get; set; }
 }