refactor: Improve documentation of NotImplementedAttribute

src/Uno.Foundation/NotImplementedAttribute.cs

@@ -5,16 +5,29 @@
 
 namespace Uno
 {
+	/// <summary>
+	/// Marks a member or symbol as not implemented by Uno.
+	/// </summary>
 	[System.AttributeUsage(AttributeTargets.All, Inherited = false, AllowMultiple = false)]
 	public sealed class NotImplementedAttribute : Attribute
 	{
+		/// <summary>
+		/// Creates an instance
+		/// </summary>
 		public NotImplementedAttribute() { }
 
+		/// <summary>
+		/// Creates an instance with C# constants for which the symbol is not implemented.
+		/// </summary>
+		/// <param name="platforms">The list of not-implemented platforms</param>
 		public NotImplementedAttribute(params string[] platforms)
 		{
 			Platforms = platforms;
 		}
 
+		/// <summary>
+		/// The list of platforms that are not implemented. When empty, all platforms are not implemented.
+		/// </summary>
 		public string[]? Platforms { get; }
 	}
 }