Explicit Max Sizes

I got some feedback from someone that told me my autosignature would almost give him seizures (sorry about that btw).

When I was changing my stuff, the site said the maximum image width and height limit was exceeded. But what are the exact maximum values?

Anyways, I got my stuff sorted. Just added something decent enough that doesn't take too much screen space and doesn't give you any health issues lol.

I am just suggesting giving out the values on these warnings, so people can have somewhat of a clue of what image sizes they can and cannot upload.

@Markiemm#73466 Keep the tag at suggestions, please. I was suggesting you to add the values to the alerts.