Update calendar menu screenshots and check text
According to the "Calendar Menu Updates" section on https://blogs.gnome.org/shell-dev/2020/09/08/the-road-to-mutter-gnome-shell-3-38/ , https://gitlab.gnome.org/GNOME/gnome-user-docs/raw/master/gnome-help/C/figures/shell-appts.png and the translated versions need updates.