Autogenerate example screenshots and asciinema examples

[maralorn]

[davidak]

Aral Balkan has a script to generate localised screenshots of elementary OS Apps that can give you an idea how it can be done.

template: https://github.com/small-tech/watson/blob/main/template/task/take-screenshots for his comet app: https://github.com/small-tech/comet/blob/main/task/take-screenshots

example: https://comet.small-web.org/ result: https://github.com/small-tech/comet-screenshots