documentation update

Core/Collections/Map.cs

@@ -2,6 +2,11 @@ using System.Collections;
 
 namespace Just.Core.Collections;
 
+/// <summary>
+/// A 2D grid container providing indexer access, enumeration as <see cref="MapPoint{T}"/> values,
+/// and conversion to a 2D array. Coordinates are clamped to valid ranges.
+/// </summary>
+/// <typeparam name="T">The type of elements in the map.</typeparam>
 public class Map<T> : IMap<T>
 {
     internal readonly T[] _values;