add mention to get_pixels

Author: villares

py5_docs/Reference/api_en/Py5Image_copy.txt

@@ -27,6 +27,8 @@ Copies a region of pixels from one image into another. If the source and destina
 
 This function ignores [](sketch_image_mode).
 
+If you want to create a new image with the contents of a rectangular region of a `Py5Image` object, check out the [](py5image_get_pixels) method, where x, y, w, h, are the position and dimensions of the area to be copied. It will return a `Py5Image object`.
+
 @@ example
 image = Py5Image_copy_0.png