Added the image uploads in forms tutorial

[a-mere-peasant]

The tutorial was sorted chronologically : image uploads in forms by @lb-

Closes #5284

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[lb-]

@a-mere-peasant - what name did you want on the contributors list?

[lb-]

@a-mere-peasant - this has been merged in, thanks for getting those fixes up

let me know if you want your name revised in the contributors list - just @ me on this PR

1eae1e4