Dosbox-core has no logo, paint one

[Proletar666]

Dosbox-core has no official logo.

Pure has one, can find it on its GitHub front page:

https://github.com/schellingb/dosbox-pure/blob/main/images/logo.png

Actually, all other active DOSBox projects have one:

X:

https://www.steamgriddb.com/game/5363105/icons

Staging:

https://commons.m.wikimedia.org/wiki/File:Dosbox_Staging_icon,_2020.svg

Even vanilla DOSBkox (which is comatose on life support) has one:

https://commons.m.wikimedia.org/wiki/File:DOSBox_icon.png

Dosbox-core needs something similar. A small PNG file, around 200×200 pixels