Update Image.swift

Fix func description

Sources/Image/Image.swift

@@ -355,7 +355,7 @@ extension KingfisherWrapper where Base: KFCrossPlatformImage {
     /// input image in pixel format. It does downsampling from the image data, so it is much
     /// more memory efficient and friendly. Choose to use downsampling as possible as you can.
     ///
-    /// The input size should be smaller than the size of input image. If it is larger than the
+    /// The pointsize should be smaller than the size of input image. If it is larger than the
     /// original image size, the result image will be the same size of input without downsampling.
     public static func downsampledImage(data: Data, to pointSize: CGSize, scale: CGFloat) -> KFCrossPlatformImage? {
         let imageSourceOptions = [kCGImageSourceShouldCache: false] as CFDictionary