Update kapp-controller asciinema video to show more realistic PackageRepository

[danielhelfand]

Currently, the kapp-controller webpage features a small demo video shown here. The PackageRepository shown in the video features sample Packages (i.e. simple-app.corp.com).

However, changing this to showcase a repository with more meaningful Packages (e.g. cert-manager) would help users better understand kapp-controller. Using the simple-app Package isn't the perfect illustration of kapp-controller's capabilities.

The asciinema video is maintained here in the carvel repo. There should also be some discussion about what PackageRepository to use in the video.