Update README.md

Add the note about the use of Image Processing Toolbox in Arrays.mlx

Author: eszmw

README.md

@@ -49,7 +49,7 @@ Ensure you have all the required products ([listed below](#H_E850B4FF)) installe
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 ## Products
 
-MATLAB® is used throughout.
+MATLAB® is used throughout. The `imsplit` command in `Arrays.mlx` is from the Image Processing Toolbox&trade;.
 
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 # Scripts