Stickers!

Adds Sierpiński sticker and hex-sticker-1 (postmarketOS logo sticker for #FOSSY2024).

Stickers must be printed according to the standard hexagon laptop sticker size (2 inches on the longest diameter of hexagon).

See this Desmos graph if there is any confusion for sizes. The side length of Sierpiński Triangle sticker if made should be as close as to sqrt(3)inches (about 1.732 inches or 1& 3/4 in. (ugh imperial!)) as possible.