Update Rgb48.cs

Author: n0099

src/ImageSharp/PixelFormats/PixelImplementations/Rgb48.cs

@@ -8,7 +8,7 @@
 namespace SixLabors.ImageSharp.PixelFormats;
 
 /// <summary>
-/// Packed pixel type containing three 16-bit unsigned normalized values ranging from 0 to 635535.
+/// Packed pixel type containing three 16-bit unsigned normalized values ranging from 0 to 65535.
 /// <para>
 /// Ranges from [0, 0, 0, 1] to [1, 1, 1, 1] in vector form.
 /// </para>