relaunch: update video

The current video that is linked here https://mray-guest.pages.debian.net/freedombox.org-relaunch/images/lime/ is outdated.

Things that need to be addressed:

• mention that you can buy a ready made set ;) (but don't mention olimex as we may change our preference where to link)
• show how things work on the new homepage
• "balena" is called "etcher" now https://www.balena.io/etcher/
• don't suggest extracting the image
• I'd propose to not point out the division into "three partitions" – people may not know what that is and it is not important
• don't cover installation of apps! ("should" be obvious and UI hopefully changes soon)
• don't cover powering down FreedomBox (out of scope, too)
• maybe mention discuss.freedombox.org at the end?

By focusing on just the installation with the points mentioned above we can drastically reduce the run time of the video, which is great.