added general event-related design files

events/rollup-product-model.md

+ The rollup we bought is the following model: https://www.flyeralarm.com/de/p/roll-up-classic-system-inkl-druck-4241304.html   (85 x 200 cm)
+
+ This is relevant because in this model the canvas can be replaced, so only a new canvas needs to be bought and not the whole casing etc.