add documentation for image layouts

[johnnychen94]

The contents are quite self-explained here, I'm most familiar with images so I try to explain everything I know about images, and hopefully, the same reasoning applies to other data types as well. I'm not Flux, CUDA, or performance expert, I'm not a native English speaker, please feel free to make suggestions on whether the contents or the word choices.

[darsnack]

Mostly left some minor comments, but this is amazing! Thanks for taking the time to write it up; I know it will benefit a lot of users.

[johnnychen94]

#1705 (comment)
I was thinking this would be a one-time manual step where one of us just runs through all the code in the table and makes note of the ones that error. Then we add a parenthetical for the ones that break AD.

I'm afraid that I don't have time to do this recently. I'll come back when I'm available and resolve any further comments together.