I am making a computer application that I will receive payment for. I have found an image online with a creative commons license (CC BY) allowing it to be used for any purpose with attribution, and I wish to use this image in my program. I plan to say "[image name] image courtesy of [the creator] used under Creative Commons license" along with a link to their page in the README file. Is this appropriate attribution, or how could it be done better?
The licence tells you what you must do:
Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
I highlighted the important point: they tell you what you must do, the how is up to you so long as it is reasonable.