fix comment

Author: shimat

src/OpenCvSharp/Modules/core/Mat/Mat.cs

@@ -299,7 +299,9 @@ public static Mat FromPixelData(int rows, int cols, MatType type, IntPtr data, l
     }
 
     /// <summary>
-    /// constructor for matrix headers pointing to user-allocated data
+    /// Constructor for matrix headers pointing to user-allocated data.
+    /// **Do not use this constructor directly.** Please use <see cref="Mat.FromPixelData"/> instead.
+    /// This constructor was removed from the public API because the introduction of <c>nint</c> in .NET caused overload resolution confusion.
     /// </summary>
     /// <param name="rows">Number of rows in a 2D array.</param>
     /// <param name="cols">Number of columns in a 2D array.</param>
@@ -320,7 +322,7 @@ protected Mat(int rows, int cols, MatType type, Array data, long step = 0)
     }
 
     /// <summary>
-    /// constructor for matrix headers pointing to user-allocated data
+    /// Constructor for matrix headers pointing to user-allocated data.
     /// </summary>
     /// <param name="rows">Number of rows in a 2D array.</param>
     /// <param name="cols">Number of columns in a 2D array.</param>