Earlier versions of widgets (ex. Quick Links) would specify the image specifications for the images that might be uploaded. 

It’d be good to bring those back and standardize as part of the widget customization experience. 

I know that recently some image specifications/dimensions were updated to standardize across different modules/widgets. And while style guides and templates exist if you go searching, I’d rather not need to do that (and/or wonder if it’s still up-to-date) when I’m customizing widgets.