Change sample artwork

docs/assets/samples/attributions.txt

@@ -1,22 +0,0 @@
-K1_drawing
-B/W 4
-https://commons.wikimedia.org/wiki/File:K1_drawing.jpg
-
-Cityscape Sunset_DFM3-01
-Color 4,8,32
-<a href="https://www.vecteezy.com/free-vector/building">Building Vectors by Vecteezy</a>
-
-Gum Tree Vector
-Color 4,8,32
-<a href="https://www.vecteezy.com/free-vector/nature">Nature Vectors by Vecteezy</a>
-
-vectorstock_31191940
-Color 8,7,64
-<a href="https://www.vectorstock.com/royalty-free-vector/dessert-poster-design-with-chocolate-cake-mousses-vector-31191940">Vector image by VectorStock / vectorstock</a>
-
-angel-luciano-LATYeZyw88c-unsplash
-Color 10,8,48 180
-<span>Photo by <a href="https://unsplash.com/@roaming_angel?utm_source=unsplash&amp;utm_medium=referral&amp;utm_content=creditCopyText">Angel Luciano</a> on <a href="https://unsplash.com/s/photos/dog?utm_source=unsplash&amp;utm_medium=referral&amp;utm_content=creditCopyText">Unsplash</a></span>
-
-spaceships.png
-https://opengameart.org/content/spaceships-1